摘要
过渡金属氧化物因其在催化剂、催化剂载体、传感材料、电致变色装置等方面的广泛应用引起人们极大的兴趣。例如，VB、VIB族过渡金属氧化物是一种便利且有效的催化剂，可直接（单罐）将烷烃转换为相应的羧酸、醇和酮。从微观层面上了解这些过渡金属氧化物的物理化学性质，将帮助我们剪裁出具有特殊性质的新材料。对气相簇合物的研究搭建了一条有望实现该目标的桥梁，并可作为研究块材表面及催化反应机理的分子模型。气相簇合物的组成及电荷态在实验中可以通过改变实验条件得到很好的控制。在理论模拟的帮助下，我们能够使各种气相簇合物的研究“精细化”。
在本论文中,我们采用理论计算方法对一系列VB、VIB族过渡金属及其氧化物簇合物进行了研究，它们包括：三核簇合物M_3O_n~(-/0)(M=Nb, n=0-2; M=Ta, n=0-8)以及四核簇合物W_4O_n~(-/0)(n=10-13)。下面对本论文的主要工作做一简要归纳。
对于三核的铌氧化物簇合物Nb_3O_n~(-/0)(n=0-2)来说，我们采用密度泛函理论计算的方法来研究它们的几何与电子结构、化学成键以及它们的顺序氧化过程。我们发现Nb_3O~(2-)具有低对称性C_1(~1A)，且两个氧原子分别为一个桥氧和一个端氧。端氧Nb=O在铌氧化物催化剂中很常见，Nb_3O~(2-)簇合物可以作为研究催化剂活性位以及金属铌表面初步氧化的分子模型。
对于VB族的另一重金属元素钽，我们对其裸金属簇Ta_3~(-/0)进行了理论研究。我们发现Ta~(3-)具有多重的d轨道芳香性，该芳香性正好与其D3h高对称性相对应。进一步的分子轨道分析被用来阐述其化学成键方面的性质。
在研究Ta_3~(-/0)裸簇基础上，我们对一系列钽氧化物簇合物Ta3On-/0(n=1-8)的顺序氧化行为进行了研究。文中我们对Ta3On-/0(n=1-8)簇合物的几何及电子结构的演化过程也进行了详细考察。
除了上述工作，我们还对一系列VIB族的四核钨氧化物簇合物W_4O_n~(-/0)(n=10-13)进行了理论研究。阐述了它们在几何及电子结构上的演化，发现W4O11
含有一个定域的W~(3+)位，可以和O_2反应形成W_4O_(13)~-簇合物。分子轨道分析被用来理解该系列簇合物的化学成键，并进一步阐释了它们的电子及几何结构的演化过程。
Transition metal oxides (TMOs) have attracted considerable interest dueto their wide applications in catalysis, catalyst support, sensor materials,electrochromic devices and so forth. For example, group VB/VIB metaloxides are convenient and efficient catalysts for the direct (single-pot)conversion of alkanes to the corresponding carboxylic acids, alcohols andketones. The understanding of their chemical and physical properties at themicroscopic level will help us to design the materials with desired properties.Studies on the gas-phase clusters may build a bridge to this goal. Molecularclusters of TMOs have been considered as models for surfaces and catalyticreaction mechanism. Both experimental and theoretical approaches have beenemployed to investigate the TMO clusters. The compositions and chargestates of gas-phase clusters can be well controlled through experimentalconditions. With the aid of quantum chemical calculation, we are able tostudy these clusters more elaborately.
In this dissertation, the theoretical studies on a series of group VB/VIBtransition metal and their oxide clusters are presented, i.e., the trinuclear M3On-/0(M=Nb, n=0-2; M=Ta, n=0-8) and the tetranuclear W4On-/0(n=10-13)clusters. A summary of our work is given as following:
For the trinuclear niobium oxide clusters, Nb3On/0(n=0-2), DFTcalculations were used to investigate the structural and electronic properties,chemical bonding and their sequential oxidation. We found that Nb3O2possesses a low symmetry C1(1A) structure, which contains a bridging and aterminal O atom. The terminal Nb=O unit is common in niobia catalysts andthe Nb3O2cluster with a Nb=O unit may be viewed as a molecular model forthe catalytic sites or the initial oxidation of a Nb surface.
As for the heavier element of group VB, i.e., tantalum, its bare metalcluster Ta3/0was investigated using density functional theory calculations.Multiple d-orbital aromaticity was found for the Ta3ground-state,commensurate with its highly symmetric D3hstructure. A detailed molecularorbital analysis was performed to elucidate the chemical bonding in Ta3-.
Then, theoretical study on the sequential oxidation behaviors oftritantalum oxide clusters, Ta3On-/0(n=1-8), were performed using densityfunctional theory calculations. The evolutions of geometric and electronicstructures were elaborated for the clusters, Ta3On-/0(n=1-8).
We also reported the theoretical calculations for a series of tetratungstenoxide clusters, W4On-/0(n=10-13). The evolutions of geometric andelectronic structures were presented. We showed that W4O11contains alocalized W3+site, which can readily react with O2to form the W4O13cluster.Molecular orbital analyses were performed to analyze the chemical bonding inthe tetratungsten oxide clusters and to elucidate their electronic and structuralevolution.
引文
[1] Xu X., Faglioni F., Goddard W. A., III Methane activation by transition-metaloxides, MOx(M=Cr, Mo, W; x=1,2,3). J. Phys. Chem. A2002,106:7171-7176.
[2] Qu Z. W., Kroes G. J. Theoretical study of stable, defect-free (TiO2)nnanoparticles with n=10-16. J. Phys. Chem. C2007,111:16808-16817.
[3] Waters T., O’Hair R. A. J., Wedd A. G. Gas-phase reactivity of heterobinuclearoxometalate anions [CrMoO-6(OR)]-,[CrWO6(OR)], and [MoWO6(OR)]-(R=H,nBu). Inorg. Chem.2005,44:3356-3366.
[4] Li J., Li X., Zhai H. J., et al. Au20: A tetrahedral cluster. Science2003,299:864-867.
[5](a) Ziegler T. Approximate density functional theory as a practical tool inmolecular energetics and dynamics. Chem. Rev.1991,91:651-667.(b) Parr, R.G., Yang, W. Density-functional theory of atoms and molecules; Oxford:Oxford University Press,1989.
[6](a) M ller C., Plesset M. S. Note on an approximation treatment formany-electron systems. Phys. Rev.1936,46:618-622.(b) Pople J. A., BinkleyJ. S., Seeger R. Theoretical models incorporating electron correlation. Int. J.Quantum Chem.1976,10:1-19.(c) Krishnan R., Pople J. A. Approximatefourth-order perturbation theory of the electron correlation energy. Int. J.Quantum Chem.1978,14:91-100.
[7](a) Raghavachari K., Pople J. A. Calculation of one-electron properties usinglimited configuration interaction techniques. Int. J. Quantum Chem.1981,20:1067-1071.(b) Krishnan R., Schlegel H. B., Pople J. A. Derivative studies inconfiguration–interaction theory. J. Chem. Phys.1980,72:4654-4655.(c)Szabo A., Ostlund N. S. Modern quantum chemistry: introduction to advancedelectronic structure theory; New York: Macmillan Publishing Co., Inc.,1982.
[8] Chong D. P., Langhoff S. R. A modified coupled pair functional approach. J.Chem. Phys.1986,84:5606-5610.
[9] Pople J. A., Head-Gordon M., Raghavachari K. Quadratic configurationinteraction. A general technique for determining electron correlation energies. J.Chem. Phys.1987,87:5968-5979.
[10](a) Bartlett R. J. Many-body perturbation theory and coupled cluster theory forelectron correlation in molecules. Annu. Rev. Phys. Chem.1981,32:359-401.(b) Scuseria G. E., Schaefer H. F., III Is coupled cluster singles and doubles(CCSD) more computationally intensive than quadratic configurationinteraction (QCISD)? J. Chem. Phys.1989,90:3700-3703.
[11] Raghavachari K., Trucks G. W., Pople J. A., et al. A fifth-order perturbationcomparison of electron correlation theories. Chem. Phys. Lett.1989,157:479-483.
[12] Moore J. H., Spencer N. D. Encyclopedia of chemical physics and physicalchemistry; Philadelphia: IOP Publishing Inc.,2001.
[13] Tolbert S. H., Alivisatos A. P. High-pressure structural transformations insemiconductor nanocrystals. Annu. Rev. Phys. Chem.1995,46:595–626.
[14] Chen C. C., Herhold A. B., Johnson C. S., et al. Size dependence of structuralmetastability in semiconductor nanocrystals. Science1997,276:398–401.
[15] Alivisatos A. P. Perspectives on the physical chemistry of semiconductornanocrystals. J. Phys. Chem.1996,100:13226–13239.
[16] Jena P., Khanna S. N., Rao B. K. Physics and chemistry of small metal clusters;New York: Plenum,1987.
[17] Khanna S. N., Castleman A. W., Jr. Quantum phenomena in clusters andnanostructures; Berlin: Springer,2003.
[18] Jellinek J. Theory of atomic and molecular clusters: with a glimpse atexperiments, Berlin: Springer Series in Cluster Physics,1999.
[19](a) Meiwes-Broer K. H. Metal clusters at surfaces, Berlin: Springer series inCluster Physics,1999.(b) de Heer W. A., Knight W. D., Chou M. Y., et al.Electronic shell structure and metal clusters. Solid State Phys.1987,40:93-181.(c) de Heer W. A., The physics of simple metal clusters: experimental aspectsand simple models. Rev. Mod. Phys.1993,65:611-676.(d) Bonacic-KouteckyV., Fantucci P., Koutecky J. Quantum chemistry of small clusters of elementsof groups Ia, Ib, and IIa: fundamental concepts, predictions, and interpretationof experiments. Chem. Rev.1991,91:1035-1108.(e) Knight W. D., ClemengerK., de Heer W. A., et al., Electronic shell structure and abundances of sodiumclusters Phys. Rev. Lett.1984,52:2141-2143.(f) Ekardt, W. Work function ofsmall metal particles: Self-consistent spherical jellium-background model. Phys.Rev. B1984,29:1558-1564.(g) Cohen M. L., Chou M. Y., Knight W. D. et al.,Physics of metal clusters. J. Phys. Chem.1987,91:3141-3149.
[20] Fialko E. F., Kikhtenko A. V., Goncharov V. B., et al. Similarities betweenreactions of methanol with MoxOy+in the gas-phase and over real catalysts. J.Phys. Chem. B1997,101:5772-5773.
[21](a) Haberland H., Cluster of atoms and molecules I, Berlin: Springer Series inChemical Physics,1995.(b) Duncan M. A. Advances in metal andsemiconductor clusters, University of Georgia: JAI Press, Inc.,1993-1998;Elsevier Science Publishers,2001.
[22] Gong Y., Zhou M. F., Andrews L. Spectroscopic and theoretical studies oftransition metal oxides and dioxygen complexes. Chem. Rev.2009,109:6765–6808.
[23] Weis P., Gilb S., Gerhardt P., et al. A time-of-flight, drift cell, quadrupoleapparatus for ion mobility measurements. Int. J. Mass. Spectrom.2002,216:59-73.
[24] Wrenger B., Meiwes-Broer K. H. The application of a Wien filter to massanalysis of heavy clusters from a pulsed supersonic nozzle source. Rev. Sci.Instrum.1997,68:2027-2030.
[25] Knickelbein M. B. The spectroscopy and photophysics of isolatedtransitionmetal clusters. Philosoph. Mag. B1999,79:1379-1400.
[26] Rodgers M. T., Armentrout P. B. Noncovalent metal-ligand bond energies asstudied by threshold collision-induced dissociation. Mass Spectrom.Rev.2000,19:215-247.
[27] Armentrout P. B. Reactions and thermochemistry of small transition metalcluster ions. Annu. Rev. Phys. Chem.2001,52:423-461.
[28] Vakhtin A., Sugawara K. FT-ICR study on hydrogenation of niobium clustercations Nb+n(n=2–15) in seeded supersonic jet and multiple-collision-induceddissociation of Nb+nHmhydrides. J. Chem. Phys.1999,111:10859-10865.
[29] Gough T. E., Mengel M., Rowntree P. A. et al., Infrared spectroscopy at thesurface of clusters: SF6on Ar. J. Chem. Phys.1985,83:4958-4961.
[30] Burton G. R., Xu C., Arnold C. C., et al. Photoelectron spectroscopy and zeroelectron kinetic energy spectroscopy of germanium cluster anions. J. Chem.Phys.1996,104:2757-2764.
[31] Pontius N., Bechthold P. S., Neeb M., et al. Ultrafast hot-electron dynamicsobserved in pt3-using time-resolved photoelectron spectroscopy. Phys. Rev. Lett.2000,84:1132-1135.
[32] Weis, P. Structure determination of gaseous metal and semi-metal cluster ionsby ion mobility spectrometry. Int. J. Mass. Spectrom.2005,245:1-13.
[33] Eland J. H. D., Photoelectron spectroscopy, London: Butterworths,1984.
[34] Leopold D. G., Ho J., Lineberger W. C. Photoelectron spectroscopy ofmass-selected metal cluster anions. I. Cu-nn=1–10. J. Chem. Phys.1987,86:1715-1726.
[35] Pettiette C. L., Yang S. H., Craycraft M. J., et al. Ultraviolet photoelectronspectroscopy of copper clusters. J. Chem. Phys.1988,88:5377-5382.
[36] Gantef r G., Gausa M., Meiwes-Broer K. H., et al. Photoelectron spectroscopyof silver and palladium cluster anions. Electron delocalization versus,localization. J. Chem. Soc., Faraday Trans.1990,86:2483-2488.
[37] Lippa T. P., Xu S. J., Lyapustina S. A., et al. Zinc oxide and its anion: Anegative ion photoelectron spectroscopic study. J. Chem. Phys.1998,109:8426-8429.
[38](a) Arnold C. C., Neumark D. M. Advances in metal and semiconductorclusters vol. III. Greenwich: JAI Press,1995,113-148.(b) Bragg A. E., Verlet J.R. R., Kammrath A., et al. Hydrated electron dynamics: From clusters to bulk.Science2004,306:669-671.
[39] Paik D. H., Lee I., Yang D., et al. Electrons in finite-sized water cavities:Hydration dynamics observed in real time. Science2004,306:672-675.
[40] Pramann A., Koyasu K., Nakajima A., et al. Anion photoelectron spectroscopyof VnO-m(n=4–15; m=0–2). J. Chem. Phys.2002,116:6521-6528.
[41](a) Wu H., Desai S. R., Wang L. S. Evolution of the electronic structure ofsmall vanadium clusters from molecular to bulklike. Phys. Rev. Lett.1996,77:2436-2439.(b) Li X., Wu H., Wang X. B., et al. s-p Hybridization and electronshell structures in aluminum clusters: a photoelectron spectroscopy study. Phys.Rev. Lett.1998,81:1909-1912.
[42](a) Hoffmann M. A., Wrigge G., Issendorff B.v., et al. Ultraviolet photoelectronspectroscopy of Si－－4to Si1000. Eur. Phys. J. D2001,16:9-11.(b) HoffmannM. A., Wrigge G., Issendorff B.v. Photoelectron spectroscopy of Al-32000:Observation of a “Coulomb staircase” in a free cluster. Phys. Rev. B2002,66:041404(3).(c) Prinzbach H., Weiler A., Landenberger P., et al. Gas-phaseproduction and photoelectron spectroscopy of the smallest fullerene, C20.Nature2000,407:60-63.
[43](a) Gantef r G., Eberhardt W. Localization of3d and4d electrons in smallclusters: The “roots” of magnetism. Phys. Rev. Lett.1996,76:4975-4978.(b)Müller J., Liu B., Shvartsburg A. A., et al. Spectroscopic evidence for thetricapped trigonal prism structure of semiconductor clusters. Phys. Rev. Lett.2000,85:1666-1669.
[44] Hansen P. L., Wagner J. B., Helveg S., et al. Atom-resolved imaging ofdynamic shape changes in supported copper nanocrystals. Science2002,295:2053-2055.
[45] Knickelbein M. B., Reactions of transition metal clusters with small molecules.Annu. Rev. Phys. Chem.1999,50:79-115.
[46] Gittins D. I., Bethell D., Schiffrin D. J., et al. A nanometre-scale electronicswitch consisting of a metal cluster and redox-addressable groups. Nature2000,408:67-69.
[47] Park S. J., Taton T. A., Mirkin C. A. Array-based electrical detection of DNAwith nanoparticle probes. Science2002,295:1503-1506.
[48] Boal A. K., Ilhan F., DeRouchey J. E., et al. Self-assembly of nanoparticles intostructured spherical and network aggregates. Nature (London)2000,404:746-748.
[49] Binns C. Nanoclusters deposited on surfaces. Surf. Sci. Rep.2001,44:1-49.
[50] Li H. B., Tian S. X., Yang J. L. Propene Oxidation on V4O11Cluster: ReactionDynamics to Acrolein. J. Phys. Chem. A,2010,114:6542–6549.
[51] Lyalin A., Taketsugu T. Reactant-Promoted Oxygen Dissociation on GoldClusters. J. Phys. Chem. Lett.,2010,1:1752–1757.
[52] Tenorio F. J., Murray I., Martinez A., et al. Products of the addition of watermolecules to Al3O3-clusters: Structure, bonding, and electron binding energiesin Al3O4H2-, Al3O5H4-, Al3O4H2, and Al3O5H4. J. Chem. Phys.2004,120:7955-7962.
[53] Waters T., O’Hair R. A. J., Wedd A. G. Catalytic gas phase oxidation ofmethanol to formaldehyde. J. Am. Chem. Soc.2003,125:3384-3396.
[54] Justes D. R., Mitri R., Moore N. A., et al. Theoretical and experimentalconsideration of the reactions between VxOy+and ethylene. J. Am. Chem. Soc.2003,125:6289-6299.
[55] Fielicke A., Mitri R., Meijer G., et al. The structures of vanadium oxidecluster-ethene complexes. A combined IR multiple photo dissociationspectroscopy and DFT calculation study. J. Am. Chem. Soc.2003,125:15716-15717.
[56] Socaciu L. D., Hagen J., Bernhardt T. M., et al. Catalytic CO oxidation by freeAu-2: Experiment and theory. J. Am. Chem. Soc.2003,125:10437-10445.
[57](a) Fu G., Xu X., Lu X.,et al. Mechanisms of methane activation andtransformation on molybdenum oxide based catalysts. J. Am. Chem. Soc.2005,127:3989-3996.(b) Fu G., Xu X., Wan H. L. Mechanism of methane oxidationby transition metal oxides: A cluster model study. Catal. Today2006,117:133-137.
[58] Limberg C. The role of radicals in metal-assisted oxygenation reactions. Angew.Chem., Int. Ed.2003,42:5932-5954and reference therein.
[59] Fan J., Nicholas J. B., Price J. M., et al. Si3O4-: Vibrationally resolvedphotoelectron spectrum and ab initio calculations. J. Am. Chem. Soc.1995,117:5417-5418.
[60] Wang L. S., Wu H., Desai S. R., et al. A Photoelectron spectroscopic study ofsmall silicon oxide clusters: SiO2, Si2O3, and Si2O4. J. Phys. Chem.1996,100:8697-8700.
[61] Wang L. S., Desai S. R., Wu H., et al. Small silicon oxide clusters: Chains andrings. Z. Phys. D1997,40:36-39.
[62] Wang L. S., Nicholas J. B., Dupuis M., et al. Si3Oy(y=1-6) clusters: Modelsfor oxidation of silicon surfaces and defect sites in bulk oxide materials. Phys.Rev. Lett.1997,78:4450-4453.
[63] Desai S. R., Wu H., Wang L. S. Vibrationally resolved photoelectronspectroscopy of AlO-and AlO-2. Int. J. Mass Spectrom. Ion Processes1996,159:75-80.
[64] Desai S. R., Wu H., Rohfling C., et al. Structure and bonding of smallaluminum oxide clusters studied by anion photoelectron spectroscopy, Al-xOy(x=1,2, y=1-5). J. Chem. Phys.1997,106:1309-1317, and references therein.
[65] Wu H., Li X., Wang X. B., et al. Al3Oy(y=0–5) clusters: Sequential oxidation,metal-to-oxide transformation, and photoisomerization. J. Chem. Phys.1998,109:449-458.
[66] Gowtham S., Costales A., Pandey R. Theoretical study of sequential oxidationof clusters of gallium oxide: Ga3On(n=4–8) Chem. Phys. Lett.2006,431:358-363.
[67] Nicholas J. B., Fan J., Wu H., et al. A combined density functional theoreticaland photoelectron spectroscopic study of Ge2O2. J. Chem. Phys.1995,102:8277-8280.
[68] Fan J., Wang L. S. Photoelectron spectroscopy of FeO2and FeO2-: Observationof low-spin excited states of FeO and determination of the electron affinity ofFeO2. J. Chem. Phys.1995,102:8714-8717.
[69] Wang L. S., Fan J., Lou L. Iron clusters and oxygen-chemisorbed iron clusters.Surf. Rev. Lett.1996,3:695-699.
[70] Wu H., Desai S. R., Wang L. S. Observation and photoelectron spectroscopicstudy of novel mono-and diiron oxide molecules: FeOy-(y=1-4) and Fe2Oy-(y=1-5). J. Am. Chem. Soc.1996,118:5296-5301.
[71] Wang L. S., Wu H., Desai S. R. Sequential oxygen atom chemisorption onsurfaces of small iron clusters. Phys. Rev. Lett.1996,76:4853-4856.
[72] Wu H., Desai S. R., Wang L. S. Two isomers of CuO2: The Cu(O2) complexand the copper dioxide. J. Chem. Phys.1995,103:4363-4366.
[73] Wang L. S., Wu H., Desai S. R., et al. Electronic structure of small copperoxide clusters: From Cu2O to Cu2O4. Phys. Rev. B1996,53:8028-8031.
[74] Wu H., Desai S. R., Wang L. S. Chemical bonding between Cu andoxygen-copper oxides vs O2complexes: A study of CuOx(x=0-6) species byanion photoelectron spectroscopy. J. Phys. Chem. A1997,101:2103-2111.
[75] Wu H., Wang L. S. Electronic structure of titanium oxide clusters: TiO-y(y=1-3)and (TiO-2)x,(x=1-4). J. Chem. Phys.1997,107:8221-8228.
[76] Wu H., Wang L. S. A photoelectron spectroscopic study of monovanadiumoxide anions (VO-x, x=1–4). J. Chem. Phys.1998,108:5310-5318.
[77] Janssens E., Hou X. J., Neukermans S., et al. The exchange coupling in Cr3On(n=0-3) Clusters. J. Phys. Chem. A2007,111:4150-4157.
[78] Sun Q., Rao B. K., Jena P., et al. Effect of sequential oxidation on the electronicstructureof tungsten clusters. Chem. Phys. Lett.2004:387,29-34.
[79] Zhai H. J., Wang B., Huang X., et al. Probing the electronic and structuralproperties of the niobium trimer cluster and its mono-and dioxides: Nb-3OnandNb3On(n=0-2). J. Phys. Chem. A2009,113:3866-3875.
[80] Zhai H. J., Wang B., Huang X., et al. Structural evolution, sequential oxidation,and chemical bonding in tritantalum oxide clusters: Ta-3Onand Ta3On(n=1-8).J. Phys. Chem. A2009,113:9804-9813.
[81] Pramann A, Koyasu K., Nakajima A., et al. Photoelectron spectroscopy ofcobalt oxide cluster anions. J. Phys. Chem. A2002,106:4891-4896.
[82] Cox, P. A. Transition Metal Oxides Oxford: Clarendon Press,1992.
[83] Rao C. N., Raveau B., Transition metal oxides; New York: John Wiley,1998.
[84] Cotton F. A., Wilkinson G., Murillo C. A., et al. Advanced inorganic chemistry,6th ed. New York: John Wiley&Sons,1999.
[85] Hayashi C., Uyeda R., Tasaki A. Ultra-fine particles; Westwood: Noyes,1997.
[86] Henrich V. E., Cox P. A. The surface science of metal oxides; Cambridge:Cambridge University Press,1994.
[87] Somorjai G. A. Introduction to surface chemistry and catalysis; New York:Wiley-Interscience,1994.
[88] Gates B. C. Supported metal clusters: synthesis, structure, and catalysis. Chem.Rev.1995,95:511-522.
[89](a) Rainer D. R., Goodman D. W. Metal clusters on ultrathin oxide films:model catalysts for surface science studies. J. Mol. Catal. A: Chem.1998,131:259-283.(b) St. Clair T. P., Goodman D. W. Metal nanoclusters supported onmetal oxide thin films: bridging the materials gap. Top. Catal.2000,13:5-19.(c) Wallace W. T., Min B. K., Goodman D. W. The nucleation, growth, andstability of oxide-supported metal clusters. Top. Catal.2005,34:17-30.(d)Chen M. S., Goodman D. W. Catalytically active gold: From nanoparticles toultrathin films. Acc. Chem. Res.2006,39:739-746.
[90](a) Wachs I. E., Briand L. E., Jehng J. M., et al. Molecular structure andreactivity of the group V metal oxides. Catal. Today2000,57:323-330.(b)Chen Y. S., Wachs I. E. Tantalum oxide-supported metal oxide (Re2O7, CrO3,MoO3, WO3, V2O5, and Nb2O5) catalysts: synthesis, Raman characterizationand chemically probed by methanol oxidation. J. Catal.2003,217:468-477.(c)Wachs I. E. Recent conceptual advances in the catalysis science of mixed metaloxide catalytic materials. Catal. Today2005,100:79-94.(d) Wachs I. E., JehngJ. M., Ueda W. Determination of the chemical nature of active surface sitespresent on bulk mixed metal oxide catalysts. J. Phys. Chem. B2005,109:2275-2284.(e) Tian H. J., Ross E. I., Wachs I. E. Quantitative determination ofthe speciation of surface vanadium oxides and their catalytic activity. J. Phys.Chem. B2006,110:9593-9600.
[91] Jena P., Castleman A. W., Jr. Clusters: A bridge across the disciplines of physicsand chemistry. Proc. Natl. Acad. Sci. U.S.A.2006,103:10560-10569.
[92] Zhai H. J., Huang X., Cui L. F., et al. Electronic and structural evolution andchemical bonding in ditungsten oxide clusters: W-2Onand W2On(n＝1-6). J.Phys. Chem. A2005,109:6019-6030.
[93] Reilly N. M., Reveles J. U., Johnson G. E., et al. Experimental and theoreticalstudy of the structure and reactivity of Fe+mOn(m=1,2; n=1-5) with CO. J.Phys. Chem. C2007,111:19086-19097.
[94] Janssens E., Hou X. J., Neukermans S. The exchange coupling in Cr3On(n=0-3) clusters. J. Phys. Chem. A2007,111:4150-4157
[95] Zhai H. J., Wang L. S. Probing the electronic properties of dichromium oxideclusters Cr2O–n(n=1-7) using photoelectron spectroscopy. J. Chem. Phys.2006,125:164315-1-9.
[96] Reddy B. V., Khanna S. N. Chemically induced oscillatory exchange couplingin chromium oxide clusters. Phys. Rev. Lett.1999,83:3170-3173.
[97] Tono K., Terasaki A., Ohta T., et al. Chemical control of magnetism:oxidation-induced ferromagnetic spin coupling in the chromium dimerevidenced by photoelectron spectroscopy. Phys. Rev. Lett.2003,90:133402-1-4.
[98] Tono K., Terasaki A., Ohta T., et al. Chemically induced ferromagnetic spincoupling: Electronic and geometric structures of chromium–oxide clusteranions, Cr-2On(n=1–3), studied by photoelectronspectroscopy. J. Chem. Phys.2003,119:11221-11227.
[99] Veliah S., Xiang K. H., Pandey R., et al. Density functional study of chromiumoxide clusters: Structures, bonding, vibrations, and stability. J. Phys. Chem. B1998,102:1126-1135.
[100] Lau K. C., Kandalam A. K., Costales A., et al. Equilibrium geometry andelectron detachment energies of anionic Cr2O4, Cr2O5, and Cr2O6clusters.Chem. Phys. Lett.2004,393:112-117.
[101] Khanna S. N., Jena P. Assembling crystals from clusters. Phys. Rev. Lett.1992,69:1664-1667.
[102] Kiran B., Jena P., Li X., et al. Magic rule for AlnHmmagic clusters. Phys. Rev.Lett.2007,98:256802-1-4.
[103] Zubarev D. Y., Averkiev B. B., Zhai H. J., et al. Aromaticity and antiaromaticityin transition-metal systems. Phys. Chem. Chem. Phys.,2008,10:257–267.
[104] Minkin V. I., Glukhovtsev M. N., Simkin B. Ya. Aromaticity andantiaromaticity; New York: Wiley,1994.; see also special issues: Chem. Rev.2001,101(5) and Chem. Rev.2005,105(10).
[105] Li X., Kuznetsov A. E., Zhang, H. F., et al. Observation of all-metal aromaticmolecules. Science2001,291:859–861.
[106] Kuznetsov A. E., Birch K. A., Boldyrev A. I., et al. All-metal antiaromaticmolecule: Rectangular Al4–4in the Li–3Al4anion. Science2003,300:622–625.
[107] Hirsch A, Chen Z. F., Jiao H. J. Spherical aromaticity in Ihsymmetricalfullerenes: The2(N+1)2rule. Angew. Chem. Int. Ed.2000,39:3915–3917.
[108] Johansson M. P., Sundholm D., Vaara, J. Au32: A24-carat golden fullerene.Angew. Chem., Int. Ed.2004,43:2678–2681.
[109] Gu X., Ji M., Wei S. H., et al. AuNclusters (N=32,33,34,35): Cagelikestructures of pure metal atoms. Phys. Rev. B2004,70:205401-1-5.
[110] Wang J., Jellinek J., Zhao J., et al. Hollow cages versus space-filling structuresfor medium-sized gold clusters: The spherical aromaticity of the Au50cage. J.Phys. Chem. A2005,109:9265–9269.
[111] Tian D., Zhao J., Wang, B., et al. Dual relationship between large gold clusters(antifullerenes) and carbon fullerenes: A new lowest-energy cage structure forAu50. J. Phys. Chem. A2007,111:411–414.
[112] Karttunen A. J., Linnolahti M., Pakkanen T. A., et al. Icosahedral Au72: apredicted chiral and spherically aromatic golden fullerene. Chem. Commun.2008(4):465–467.
[113] Alexandrova A. N., Boldyrev A. I. σ-aromaticity and σ-antiaromaticity in alkalimetal and alkaline earth metal small clusters. J. Phys. Chem. A2003,107:554-560.
[114] Havenith R. W. A., De Proft F., Fowler P. W., et al. σ-Aromaticity in H3+andLi+3: Insights from ring-current maps. Chem. Phys. Lett.2004,407:391-396.
[115] Yong L., Wu S. D., Chi X. X. Theoretical study of aromaticity in smallhydrogen and metal cation clusters X3+(X=H, Li, Na, K, and Cu). Int. J.Quantum Chem.2007,107:722-728.
[116] Kuznetsov A. E., Corbett J. D., Wang L. S., et al. Aromatic mercury clusters inancient amalgams. Angew. Chem., Int. Ed.2001,40:3369-3372.
[117] Cotton F. A., Curtis N. F., Harris C. B., et al. Mononuclear and polynuclearchemistry of rhenium (III): Its pronounced homophilicity. Science1964,145:1305-1307.
[118] Huang X., Zhai H. J., Kiran, B., et al. Observation of d-orbital aromaticity.Angew. Chem. Int. Ed.2005,44:7251-7254.
[119] Zhai H. J., Averkiev B. B., Zubarev D. Yu., et al. δ-aromaticity in Ta-3O3. Angew.Chem. Int. Ed.2007,46:4277-4280.
[120] Averkiev B. B., Boldyrev A. I. Hf3cluster is triply (σ-, π-, and δ-) aromatic inthe lowest D3h,1A1' state. J. Phys. Chem. A2007,111:12864-12866.
[121] Tsipis A. C., Kefalidis C. E., Tsipis C. A. The role of the5f orbitals in bonding,aromaticity, and reactivity of planar isocyclic and heterocyclic uranium clusters.J. Am. Chem. Soc.2008,130:9144–9155.
[122](a) Nowak I., Ziolek M. Niobium compounds: Preparation, characterization,and application in heterogeneous catalysis. Chem. Rev.1999,99:3603-3624.(b)Ziolek M. Niobium-containing catalysts—the state of the art. Catal. Today2003,78:47-64.(c) Tanabe K. Catalytic application of niobium compounds. Catal.Today2003:78,65-77.
[123] B hme D. K., Schwarz H. Gas-phase catalysis by atomic and cluster metal ions:The ultimate single-site catalysts. Angew. Chem. Int. Ed.2005,44:2336-2354.
[124](a) Morse M. D. Clusters of transition-metal atoms. Chem. Rev.1986,86:1049-1109.(b) Loh S. K., Lian L., Armentrout P. B. Collision-induceddissociation of niobium cluster ions: transition-metal-cluster binding energies. J.Am. Chem. Soc.1989,111:3167-3176.(c) Knickelbein M. B., Yang S. H.Photoionization studies of niobium clusters: Ionization potentials for Nb2–Nb76.J. Chem. Phys.1990,93:5760-5767.
[125](a) Wang H. M., Craig R., Haouari H., et al. Spectroscopy of mass-selectedniobium trimers in argon matrices. J. Chem. Phys.1996,105:5355-5357.(b)Aydin M., Lombardi J. R. Multiphoton fragmentation spectra of zirconium andniobium cluster cations. Int. J. Mass Spectrom.2004,235:91-96.
[126] Song L., Eychmuller A., St. Pierre R. J., et al. Reaction of carbon dioxide withgaseous niobium and niobium oxide clusters. J. Phys. Chem.1989,93:2485-2490.
[127](a) Sigsworth S. W., Castleman A. W., Jr. Reaction of group V and VI transitionmetal oxide and oxyhydroxide anions with oxygen, water, and hydrogenchloride. J. Am. Chem. Soc.1992,114:10471-10477.(b) Deng H. T., Kerns K.P., Castleman A. W., Jr. Formation, structures, and reactivities of niobium oxidecluster ions. J. Phys. Chem.1996,100:13386-13392.(c) Zemski K. A., JustesD. R., Bell R. C., et al. Reactions of niobium and tantalum oxide cluster cationsand anions with n-butane. J. Phys. Chem. A2001,105:4410-4417.(d) ZemskiK. A., Justes D. R., Castleman A. W., Jr. Reactions of group v transition metaloxide cluster ions with ethane and ethylene. J. Phys. Chem. A2001,105:10237-10245.(e) Justes D. R., Moore N. A., Castleman A. W., Jr. Reactions ofvanadium and niobium oxides with methanol. J. Phys. Chem. B2004,108:3855-3862.
[128](a) Yang D. S., Zgierski M. Z., Rayner D. M., et al. The structure of Nb3O andNb3O+determined by pulsed field ionization–zero electron kinetic energyphotoelectron spectroscopy and density functional theory. J. Chem. Phys.1995,103:5335-5342.(b) Athanassenas K., Kreisle D., Collings B. A., et al.Ionization potentials of niobium cluster oxides. Chem. Phys. Lett.1993,213:105-110.
[129](a) Jackson P., Fisher K. J., Willett G. D. Some reactions and thermochemistryof NbO-3: oxidation and reduction, hydrogen bond strength, and catalyticactivation of primary alcohols. Int. J. Mass Spectrom.2000,197:95-103.(b)Jackson P., Fisher K. J., Willett G. D. The catalytic activation of primaryalcohols on niobium oxide surfaces unraveled: the gas phase reactions ofNb-xOyclusters with methanol and ethanol. Chem. Phys.2000,262:179-187.
[130] Green S. M. E., Alex S., Fleischer N. L., et al. Negative ion photoelectronspectroscopy of the group5metal trimer monoxides V3O, Nb3O, and Ta3O. J.Chem. Phys.2001,114:2653-2668.
[131] Fielicke A., Meijer G., von Helden G. Infrared spectroscopy of niobium oxidecluster cations in a molecular beam: Identifying the cluster structures. J. Am.Chem. Soc.2003,125:3659-3667.
[132] Molek K. S., Jaeger T. D., Duncan M. A. Photodissociation of vanadium,niobium, and tantalum oxide cluster cations. J. Chem. Phys.2005,123:144313-1-10.
[133] Dong F., Heinbuch S., He S. G., et al. Formation and distribution of neutralvanadium, niobium, and tantalum oxide clusters: Single photon ionization at26.5eV. J. Chem. Phys.2006,125:164318-1-8.
[134] Sambrano J. R., Andres J., Beltran A., et al. Theoretical study of the structureand stability of NbxOyand Nb+xOy(x=1–3; y=2–5,7,8) clusters. Chem. Phys.Lett.1998,287:620-626.
[135] Martinez A., Calaminici P., Koster A. M., et al. Bonding in Nb3O, Nb3S andNb3Se: A topological analysis of the electrostatic potential. J. Chem. Phys.2001,114:819-825.
[136] Calaminici P., Flores-Moreno R., Koster A. M. Structures and vibrations ofNb3O and Nb3O–: A density functional study. J. Chem. Phys.2004,121:3558-3562.
[137](a) Kietzmann H., Morenzin J., Bechthold P. S., et al. Photoelectron spectra andgeometric structures of small niobium cluster anions. Phys. Rev. Lett.1996,77:4528-4531.(b) Kietzmann H., Morenzin J., Bechthold P. S., et al. Photoelectronspectra of Nb-nclusters: Correlation between electronic structure and hydrogenchemisorption. J. Chem. Phys.1998,109:2275-2278.(c) Fournier R., Pang T.,Chen C. F. Structural characterization of niobium-cluster anions fromdensity-functional calculations. Phys. Rev. A1998,57:3683-3691.
[138] Sellers H. Ab initio and relativistic effective core potential studies ofniobium-nitrogen and niobium cluster systems. J. Phys. Chem.1990,94:1338-1343.
[139] Goodwin L., Salahub D. R. Density-functional study of niobium clusters. Phys.Rev. A1993,47: R774-R777.
[140] Gr nbeck H., Rosén A. Investigation of niobium clusters: Bare andCO-adsorption. Phys. Rev. B1996,54:1549-1552.
[141] Fowler J. E., García A., Ugalde J. M. Many low-lying isomers of the cationicand neutral niobium trimer and tetramer. Phys. Rev. A1999,60:3058-3070.
[142](a) Majumdar D., Balasubramanian K. Theoretical study of the electronic statesof niobium trimer (Nb3) and its anion (Nb-3). J. Chem. Phys.2003,119:12866-12877.(b) Majumdar D., Balasubramanian K. Theoretical study of theelectronic states of small cationic niobium clusters, Nbn+(n=3–5). J. Chem.Phys.2001,115:885-898.
[143](a) Dryza V., Addicoat M. A., Gascooke J. R., et al. Threshold photoionizationand density functional theory studies of the niobium carbide clusters Nb3Cn(n=1-4) and Nb4Cn(n=1-6). J. Phys. Chem. A2008,112:5582-5592.(b) AddicoatM. A., Buntine M. A., Yates B., et al. Associative versus dissociative binding ofCO to4d transition metal trimers: A density functional study. J. Comput. Chem.2008,29:1497-1506.
[144] Wang B., Zhang X. H., Huang X., et al. Superoxide complex [W-4O12(O2)]:Atheoretical study. Chinese J. Struct. Chem2008,27:990-994.
[145] Wang B., Chen W. J., Zhao B. C., et al. Tetratungsten oxide clusters W4On-/0(n=10-13): Structural evolution and chemical bonding. J. Phys. Chem. A2010,114:1964-1972.
[146] Wang B., Zhai H. J., Huang X., et al. On the electronic structure and chemicalbonding in the tantalum trimer cluster. J. Phys. Chem. A2008,112:10962-10967.
[147] Kohn W., Sham L. J. Self-Consistent Equations Including Exchange andCorrelation Effects. Phys. Rev.1965,140: A1133-A1138.
[148] Geerlings P., De Proft F., Langenaeker W. Conceptual Density FunctionalTheory. Chem. Rev.2003,103:1793-1874.
[149] Becke A. D. A new mixing of Hartree-Fock and local density-functionaltheories. J. Chem. Phys.1993,98:1372-1377.
[150] Lee C., Yang W., Parr R. G. Development of the Colle-Salvetticorrelation-energy formula into a functional of the electron density. Phys. Rev.B1988,37:785-789.
[151] Stephens P. J., Devlin F. J., Chabalowski C. F., et al. Ab initio calculation ofvibrational absorption and circular dichroism spectra using density functionalforce fields. J. Phys. Chem.1994,98:11623-11627.
[152] Andrae D., Haeussermann U., Dolg M., et al. Energy-adjusted ab initiopseudopotentials for the second and third row transition elements. Theor. Chim.Acta1990,77:123-141.
[153] Küchle W., Dolg M., Stoll H., et al. Pseudopotentials of the Stuttgart/DresdenGroup1998, revision August11,1998;http://www.theochem.uni-stuttgart.de/pseudopotentiale.
[154] Martin J. M. L., Sundermann A. Correlation consistent valence basis sets foruse with the Stuttgart-Dresden-Bonn relativistic effective core potentials: Theatoms Ga-Kr and In-Xe. J. Chem. Phys.2001,114:3408-3420.
[155] Dunning T. H., Jr. Gaussian basis sets for use in correlated molecularcalculations. I. The atoms boron through neon and hydrogen. J. Chem. Phys.1989,90:1007-1023.
[156] Kendall R. A., Dunning T. H., Jr., Harrison R. J. Electron affinities of thefirst-row atoms revisited. Systematic basis sets and wave functions. J. Chem.Phys.1992,96:6796-6806.
[157] Tozer D. J., Handy N. C. Improving virtual Kohn-Sham orbitals andeigenvalues: Application to excitation energies and static polarizabilities. J.Chem. Phys.1998,109:10180-10189.
[158] Frisch M. J., Trucks G. W., Schlegel H. B., et al. Gaussian03; Revision D.01;Gaussian, Inc.: Wallingford, CT,2004.
[159] Humphrey W., Dalke A., Schulten K. VMD: Visual molecular dynamics. J. Mol.Graphics1996,14:33-38.
[160] Arguably the singlet state of Nb3may be competitive. However, the VDE forthe singlet state from current DFT calculations deviates substantially from theexperiment (Table2.2). In addition the VDE pattern for the singlet state alsodisagree with the PES spectrum (ref [137a]). The assignment of a singletground-state for Nb3in ref [142a] is “not unambiguous” as those authorsnoted.
[161](a) Zhai H. J., Wang L. S., Alexandrova A. N., et al. Photoelectron spectroscopyand ab initio study of B-3and B-4anions and their neutrals. J. Phys. Chem. A2003,107:9319-9328.(b) Zhai H. J., Bürgel C., Bonacic-Koutecky V., et al.Probing the electronic structure and chemical bonding of gold oxides andsulfides in AuO-nand AuS-n(n=1,2). J. Am. Chem. Soc.2008,130:9156-9167.
[162] Molecular orbital analysis (Figure2.8) shows that the anion HOMO orbitals inNb3(5a1,81%5s+7%4d) and Nb3O(2b2,58%5s+26%4d) show strongNb5s characters, whereas that in Nb3O2(6a,70%4d+7%5s) is primarilycomposed from Nb4d orbitals. This is consistent with the observed pronouncedphoton energy dependence for Nb3and Nb3O (see ref [79]).
[163] Uhl A., Sainio J., Lahtinen J., et al. Preparation and structure of aluminasupported niobia model catalysts. Surf. Sci.2007,601:5605-5610.
[164](a) Franchy R., Bartke T. U., Gassmann P. The interaction of oxygen withNb(110) at300,80and20K. Surf. Sci.1996,366:60-70.(b) An B., FukuyamaS., Yokogawa K., et al. Surface structures of clean and oxidized Nb(100) byLEED, AES, and STM. Phys. Rev. B2003,68:115423-1-8.(c) Arfaoui I.,Cousty J., Guillot C. A model of the NbOx≈1nanocrystals tiling a Nb(110)surface annealed in UHV. Surf. Sci.2004,557:119-128.(d) Kilimis D. A.,Lekka Ch. E. Oxidation of the Nb(110) surface by ab initio calculations. Mater.Sci. Eng. B2007,144:27-31.
[165] Wang X. B., Wang L. S. Probing the electronic structure and metal-metal bondof Re2Cl82-in the gas phase. J. Am. Chem. Soc.2000,122:2096-2100.
[166] Cotton F. A., Murillo C. A., Walton, R. A. Multiple bonds between metal atoms,3rd ed. New York: Springer,2005.
[167] Nguyen T., Sutton A. D., Brynda M., et al. Synthesis of a stable compound withfive fold bonding between two chromium(I) centers. Science2005,310:844-847.
[168] Gagliardi L., Roos B. O. Quantum chemical calculations show that the uraniummolecule U2has a quintuple bond. Nature2005,433:848-851.
[169] Roos B. O., Borin A. C., Gagliardi L. Reaching the maximum multiplicity ofthe covalent chemical bond. Angew. Chem. Int. Ed.2007,46:1469-1472.
[170](a) Frenking G. Building a quintuple bond. Science2005,310:796-797.(b)Radius U., Breher F. To Boldly pass the metal-metal quadruple bond. Angew.Chem. Int. Ed.2006,45:3006-3010.(c) Frenking G., Tonner R. Theoreticalchemistry: The six-bond bound. Nature2007,446:276-277.(d) Weinhold F.,Landis C. R. Chemistry: High bond orders in metal-metal bonding. Science2007,316:61-63.
[171](a) Brynda M., Gagliardi L., Widmark P. O., et al. A quantum chemical study ofthe quintuple bond between two chromium centers in [PhCrCrPh]: Trans-bentversus linear geometry. Angew. Chem. Int. Ed.2006,45:3804-3807.(b) LaMacchia G., Brynda M., Gagliardi L. Quantum chemical calculations predictthe diphenyl diuranium compound [PhUUPh] to have a stable1Agground-state.Angew. Chem. Int. Ed.2006,45:6210-6213.(c) Roos B. O., Malmqvist P.,Gagliardi L. Exploring the actinide-actinide bond: Theoretical studies of thechemical bond in Ac2, Th2, Pa2, and U2. J. Am. Chem. Soc.2006,128:17000-17006.(d) Kreisel K. A., Yap G. P. A., Dmitrenko O., et al. The shortestmetal-metal bond yet: Molecular and electronic structure of a dinuclearchromium diazadiene complex. J. Am. Chem. Soc.2007,129:14162-14163.(e)Merino G., Donald K. J., D’Acchioli J. S., et al. The many ways to have aquintuple bond. J. Am. Chem. Soc.2007,129:15295-15302.(f) La Macchia G.,Gagliardi L., Power P. P., et al. Large differences in secondary metal-areneinteractions in the transition-metal dimers ArMMAr (Ar=Terphenyl; M=Cr,Fe, or Co): Implications for Cr-Cr quintuple bonding. J. Am. Chem. Soc.2008,130:5104-5114.
[172](a) King R. B. Chemical applications of topology and group theory.25.Electron delocalization in early-transition-metal heteropoly-andisopolyoxometalates. Inorg. Chem.1991,30:4437-4440.(b) Li J. Electronicstructures,(d-p)π conjugation effects, and spectroscopic properties ofpolyoxometalates: M6O192-(M=Cr, Mo, W). J. Cluster Sci.2002,13:137-163.(c) Tsipis A. C., Tsipis C. A. Hydrometal analogues of aromatic hydrocarbons: anew class of cyclic hydrocoppers (I). J. Am. Chem. Soc.,2003,125:1136-1137.(d) Datta A., John N. S., Kulkarni G. U., et al. Aromaticity in stable tiara-nickelthiolates: Computational and structural analysis. J. Phys. Chem. A2005,109:11647-11649.(e) Wannere C. S., Corminboeuf C., Wang Z. X., et al. Evidencefor d orbital aromaticity in square planar coinage metal clusters. J. Am. Chem.Soc.2005,127:5701-5705.(f) Chi X. X., Liu Y. Theoretical evidence ofd-orbital aromaticity in anionic metal X-3(X=Sc, Y, La) clusters. Int. J. Quant.Chem.2007,107:1886-1896.
[173](a) Alexandrova A. N., Boldyrev A. I., Zhai H. J., et al. Cu-3C4－A newsandwich molecule with two revolving C-22units. J. Phys. Chem. A2005,109:562-570.(b) Lin Y. C., Sundholm D., Juselius J., et al. Experimental andcomputational studies of alkali-metal coinage-metal clusters. J. Phys. Chem. A2006,110:4244-4250.
[174] Li S. D., Miao C. Q., Guo J. C.[Ta3O3]A (A=Li, Na, K) and [Ta3O3]B[Ta3O3](B=Ca, Sr, Ba): Sandwich-type complexes containing Ta3O3-δ and π doublearomatic ligands. Eur. J. Inorg. Chem.2008,8:1205-1209.
[175] Boldyrev A. I., Wang L. S. All-metal aromaticity and antiaromaticity. Chem.Rev.2005,105:3716-3757.
[176](a) Zhai H. J., Alexandrova A. N., Birch K. A., et al. Hepta-andocta-coordinated boron in molecular wheels of8-and9-atom boron clusters:Observation and confirmation. Angew. Chem. Int. Ed.2003,42:6004-6008.(b)Zhai H. J., Kiran B., Li J., et al. Hydrocarbon analogs of boron clusters:Planarity, aromaticity, and antiar omaticity. Nature Materials2003,2:827-833.(c) Zhai H. J., Wang L. S., Zubarev D. Yu., et al. Gold apes hydrogen. Thestructure and bonding in the planar B7Au-2and B7Au2clusters. J. Phys. Chem. A2006,110:1689-1693.(d) Sergeeva A. P., Zubarev D. Yu., Zhai H. J., et al. Aphotoelectron spectroscopic and theoretical study of B-16and B2-16: An all-boronnaphthalene. J. Am. Chem. Soc.2008,130:7244-7246.
[177] Alexandrova A. N., Boldyrev A. I., Zhai H. J., et al. All-boron aromatic clustersas potential new inorganic ligands and building blocks in chemistry. Coord.Chem. Rev.2006,250:2811-2866.
[178] Collings B. A., Rayner D. M., Hackett P. A. Ionization potentials of tantalumclusters with three to64atoms. Int. J. Mass Spectrom. Ion Processes1993,125:207-214.
[179] Fang L., Shen X., Chen X., et al. Raman spectra of ruthenium and tantalumtrimers in argon matrices. Chem. Phys. Lett.2000,332:299-302.
[180] Heaven M. W., Stewart G. M., Buntine M. A., et al. Neutral tantalum-carbideclusters: A multiphoton ionization and density functional theory study. J. Phys.Chem. A2000,104:3308-3316..
[181] Dryza V., Addicoat M. A., Gascooke J. R., et al. Ionization potentials oftantalum-carbide clusters: An experimental and density functional theory studyJ. Phys. Chem. A2005,109:11180-11190.
[182] Fa W., Luo C., Dong J. Coexistence of ferroelectricity and ferromagnetism intantalum clusters. J. Chem. Phys.2006,125:114305-1-5.
[183] Wu Z. J., Kawazoe Y., Meng J. Geometries and electronic properties of Tan,TanO and TaOn(n=1-3) clusters. J. Mol. Struct.: THEOCHEM2006,764:123-132.
[184] Li S., Alemany M. M. G., Chelikowsky J. R. Ab initio calculations for thephotoelectron spectra of vanadium clusters. J. Chem. Phys.2004,121:5893-5898.
[185](a) Zhai H. J., Kiran B., Cui L. F., et al. Electronic structure and chemicalbonding in MOn-and MOnclusters (M=Mo, W; n=3-5): A photoelectronspectroscopy and ab initio study. J. Am. Chem. Soc.2004,126:16134-16141.(b)Huang X., Zhai H. J., Waters T., et al. Experimental and theoreticalcharacterization of superoxide complexes [W-2O6(O2)] and [W-3O9(O2)]:Models for the interaction of O2with reduced W sites ontungsten oxide surfaces.Angew. Chem. Int. Ed.2006,45:657-660.(c) Zhai H. J., Wang L. S. Probingthe electronic structure and band gap evolution of titanium oxide clusters(TiO2)-n(n=1-10) using photoelectron spectroscopy. J. Am. Chem. Soc.2007,129:3022-3026.(d) Zhai H. J., Li S. G., Dixon D. A., et al. Probing theelectronic and structural properties of chromium oxide clusters (CrO3)-nand(CrO3)n(n=1–5): Photoelectron spectroscopy and density functionalcalculations. J. Am. Chem. Soc.2008,130:5167-5177.
[186] Zubarev D. Y., Boldyrev A. I., Li J., Zhai H. J., Wang L. S. On the chemicalbonding of gold in auro-boron oxide clusters Au-nBO(n=1-3). J. Phys. Chem.A2007,111:1648-1658.
[187] Wachs I. E., Chen Y., Jehng J. M., et al. Molecular structure and reactivity ofthe group V metal oxides. Catal. Today2003,78:13-24.
[188] Ushikubo T. Recent topics of research and development of catalysis by niobiumand tantalum oxides. Catal. Today2000,57:331-338.
[189](a) Ushikubo T., Wada K. Catalytic properties of hydrated tantalum oxide. Appl.Catal.1990,67:25-38.(b) Ushikubo T., Wada K. Vapor-phase beckmannrearrangement over silica-supported tantalum oxide catalysts. J. Catal.1994,148:138-148.(c) Ushikubo T., Wada K. Preparation, characterization, andcatalytic activities of silica-supported tantalum oxide for the vapor phasedecomposition of methyl tert-butyl ether. Appl. Catal. A1995,124:19-31.(d)Guiu G., Grange P. Acidic and catalytic properties of SiO2-Ta2O5mixed oxidesprepared by the sol-gel method. J. Catal.1995,156:132-138.(e) Tanaka T.,Nojima H., Yamamoto T., et al. Structure of surface tantalate species andphoto-oxidation of carbon monoxide over silica-supported tantalum oxide. Phys.Chem. Chem. Phys.1999,1:5235-5239.(f) Baltes M., Kytokivi A.,Weckhuysen B. M., et al. Supported tantalum oxide and supportedvanadia-tantala mixed oxides: Structural characterization and surface properties.J. Phys. Chem. B2001,105:6211-6220.(g) Samaranch B., de la Piscina P. R.,Clet G., et al. Synthesis and characterization of Ta2O5-ZrO2systems: Structure,surface acidity, and catalytic properties. Chem. Mater.2007,19:1445-1451.
[190](a) Zemski, K. A.; Bell, R. C.; Castleman, A. W., Jr. Reactivities of tantalumoxide cluster cations with unsaturated hydrocarbons. Int. J. Mass Spectrom.1999,184:119-128.(b) Zemski K. A., Bell R. C., Castleman A. W. Jr.Reactions of tantalum oxide cluster cations with1-butene,1,3-butadiene, andbenzene. J. Phys. Chem. A2000,104:5732-5741.
[191] Fielicke A., Meijer G., von Helden G. Infrared multiple photon dissociationspectroscopy of transition metal oxide cluster cations. Eur. Phys. J. D2003,24:69-72.
[192] Zheng W. J., Li X., Eustis S., et al. Anion photoelectron spectroscopy of TaO-n(n=1–3). Chem. Phys. Lett.2008,460:68-71.
[193](a) Premaswarup D., Barrow R. F. Rotational analysis of the tantalum oxidebands. Nature1957,180:602-603.(b) Weltner, W., Jr.; McLeod, D., Jr.Spectroscopy of TaO and TaO2in neon and argon matrices at4°and20°K. J.Chem. Phys.1965,42:882-891.(c) Cheetham, C. J.; Barrow, R. F. Rotationalanalysis of electronic bands of gaseous TaO. Trans. Faraday Soc.1967,63:1835-1845.(d) Brittain R., Powell D., Kreglewski M., et al. The magneticcircular dichroism spectrum of matrix-isolated TaO. Chem. Phys.1980,54:71-78.(e) Dyke J. M., Ellis A. M., Feher M., et al. High-temperaturephotoelectron spectroscopy. A study of niobium monoxide and tantalummonoxide. J. Chem. Soc., Faraday Trans.21987,83:1555-1565.(f) Ram R. S.,Bernath P. F. Fourier transform emission spectroscopy of TaO. J. Mol.Spectrosc.1998,191:125-136.(g) Zhou M. F., Andrews L. Reactions oflaser-ablated niobium and tantalum atoms with oxygen molecules: Infraredspectra of niobium and tantalum oxide molecules, anions, and cations. J. Phys.Chem. A1998,102:8251-8260.(h) Chen M., Wang X., Zhang L., et al.Matrix-isolation infrared spectroscopic studies on ablated products generatedfrom laser ablation of Ta2O5and Ta in ambient O2/Ar gas. Chem. Phys.1999,242:81-90.(i) Al-Khalili A., Hallsten U., Launila O. Spectroscopy of TaO. J.Mol. Spectrosc.1999,198:230-238.(j) Ram R. S., Bernath P. F. Emissionspectroscopy of two new systems of TaO. J. Mol. Spectrosc.2003,221:7-12.(k)Manke K. J., Vervoort T. R., Kuwata K. T., et al. Electronic spectrum of TaOand its hyperfine structure. J. Chem. Phys.2008,128:104302-1-6.
[194](a) Dolg M., Stoll H., Preuss H., et al. Relativistic and correlation effects forelement105(hahnium, Ha): a comparative study of M and MO (M=Nb, Ta,Ha) using energy-adjusted ab initio pseudopotentials. J. Phys. Chem.1993,97:5852-5859.(b) Rakowitz F., Marian C. M., Seijo L., et al. Spin-free relativisticno-pair ab initio core model potentials and valence basis sets for the transitionmetal elements Sc to Hg. Part I. J. Chem. Phys.1999,110:3678-3686.(c)Rakowitz F., Marian C. M., Seijo L. Spin-free relativistic no-pair ab initio coremodel potentials and valence basis sets for the transition metal elements Sc toHg. II. J. Chem. Phys.1999,111:10436-10443.
[195] Zhai H. J., D bler J., Sauer J., et al. Probing the electronic structure of earlytransition-metal oxide clusters: Polyhedral cages of (V-2O5)n(n=2-4) and(M-2O5)2(M=Nb, Ta). J. Am. Chem. Soc.2007,129:13270-13276.
[196](a) Noor A., Wagner F. R., Kempe R. Metal-metal distances at the limit: Acoordination compound with an ultrashort chromium-chromium bond. Angew.Chem., Int. Ed.2008,47:7246-7249.(b) Nguyen T., Merrill W. A., Ni C., et al.Synthesis and characterization of the metal(I) dimers [Ar’MMAr’]:Comparisons with quintuple-bonded [Ar’CrCrAr’]. Angew. Chem., Int. Ed.2008,47:9115-9117.(c) Tsai Y. C., Hsu C. W., Yu J. S., et al. Remarkably shortmetal-metal bonds: A lantern-type quintuply bonded dichromium(I) complex.Angew. Chem., Int. Ed.2008,47:7250-7253.(d) Hsu C.W., Yu J. S. K., Yen C.H., et al. quintuply-bonded dichromium(I) Complexes featuring metal-metalbond lengths of1.74. Angew. Chem., Int. Ed.2008,47:9933-9936.(e)Horvath S., Gorelsky S. I., Gambarotta S., et al. Breaking the1.80barrier ofthe Cr-Cr multiple bond between CrII atoms. Angew. Chem., Int. Ed.2008,47:9937-9940.
[197] They have recently shown in a combined experimental and theoretical studythat the B3LYP level of theory performs very well for the Ta3O3cluster.[119]The current calculations on Ta3On/0(n=1-8) were done using the same methodand basis sets.
[198] Baird N. C. Quantum organic photochemistry. II. Resonance and aromaticity inthe lowest3.pi..pi.*state of cyclic hydrocarbons. J. Am. Chem. Soc.1972,94:4941-4948.
[199](a) King R. B., Braitsch D. M., Kapoor P. N. Organometallic chemistry of thetransition metals. XXIX. Redox systems in hexamethylbenzene clustercompounds of niobium and tantalum. J. Am. Chem. Soc.1975,97:60-64.(b)Cotton F. A., Kibala P. A., Roth W. J. Synthesis by spontaneous self-assemblyof metal atom clusters of zirconium, niobium, and tantalum. J. Am. Chem. Soc.1988,110:298-300.(c) Smith M. D., Miller G. J. Novel tantalum chalcogenidehalides: The first Ta3clusters in the solid state. J. Am. Chem. Soc.1996,118:12238-12239.(d) Kawaguchi H., Tatsumi K. Synthesis of(Pentamethylcyclopentadienyl) tantalum sulfido complexes via C-S bondcleavage of triphenylmethanethiolate and formation of a novel trithioboratoligand. Organometallics1997,16:307-309.(e) Smith M., Miller G. J.Ta3SBr7—A new structure type in the M3QX7family (M=Nb, Ta; Q=S, Se,Te; X=Cl, Br, I). J. Solid State Chem.1998,140:226-232.
[200] Pyykk P. Relativistic effects in structural chemistry. Chem. Rev.1988,88:563-594.
[201] Manno D., Serra A., Giulio M. D., et al. Physical and structural characterizationof tungsten oxide thin films for NO gas detection. Thin Solid Films1998,324:44-51.
[202] Moulzolf S. C., LeGore L. J., Lad R. J. Heteroepitaxial growth of tungstenoxide films on sapphire for chemical gas sensors. Thin Solid Films2001,400:56-63.
[203] Granqvist C. G. Electrochromic tungsten oxide films: Review of progress1993–1998. Solar Energy Mater. Solar Cells2000,60:201-262.
[204] Bessière A., Marcel C., Morcrette M., et al. Flexible electrochromic reflectancedevice based on tungsten oxide for infrared emissivity control. J. Appl. Phys.2002,91:1589-1594.
[205] Salvatl L. Jr., Makovsky L. E., Stencel J. M., et al. Surface spectroscopic studyof tungsten-alumina catalysts using x-ray photoelectron, ion scattering, andRaman spectroscopies. J. Phys. Chem.1981,85:3700-3707.
[206] Horsley J. A., Wachs I. E., Brown J. M., et al. Structure of surface tungstenoxide species in the tungsten trioxide/alumina supported oxide system fromX-ray absorption near-edge spectroscopy and Raman spectroscopy. J. Phys.Chem.1987,91:4014-4020.
[207] Gazzoli D., Valigi M., Dragone R., et al. Characterization of thezirconia-supported tungsten oxide system by laser Raman and diffusereflectance spectroscopies. J. Phys. Chem. B1997,101:11129-11135.
[208] Bigey C., Hilaire L., Maire G. WO3–CeO2and Pd/WO3–CeO2as potentialcatalysts for reforming applications: I. Physicochemical characterization study.J. Catal.2001,198:208-222.
[209] Ji S. F., Xiao T. C., Li S. B., et al. The relationship between the structure andthe performance of Na-W-Mn/SiO2catalysts for the oxidative coupling ofmethane. Appl. Catal. A: Gen2002,225:271-284.
[210] Mamede A. S., Payen E., Grange P., et al. Activity behavior of samaria-dopedceria-supported copper oxide catalyst and effect of heat treatments of supporton carbon monoxide oxidation. J. Catal.2004,223:1-9.
[211] Weinstock I. A., Barbuzzi E. M. G., Wemple M. W., et al. Equilibratingmetal-oxide cluster ensembles for oxidation reactions using oxygen in water.Nature.2001,414:191-195.
[212] Zemski K. A., Justes D. R., Castleman A. W. Jr. Studies of metal oxideclusters: Elucidating reactive sites responsible for the activity of transitionmetal oxide catalysts. J. Phys. Chem. B2002,106:6136-6148.
[213](a) Vyboishchikov S. F., Sauer J.(V2O5)nGas-phase clusters (n=1-12)compared to V2O5crystal: DFT calculations. J. Phys. Chem. A2001,105:8588-8598.(b) Asmis K. R., Santambrogio G., Brümmer M., et al. Polyhedralvanadium oxide cages: Infrared spectra of cluster anions and size-induced delectron localization. Angew. Chem., Int. Ed.2005,44:3122-3125.
[214] Asmis K. R., Brümmer M., Kaposta C., et al. Mass-selected infraredphotodissociation spectroscopy of V+4O10. Phys. Chem. Chem. Phys.2002,4:1101-1104.
[215] Shi Y., Ervin K. M. Catalytic oxidation of carbon monoxide by platinum clusteranions. J. Chem. Phys.1998,108:1757-1760.
[216] Asmis K. R., Meijer G., Brümmer M., et al. Gas phase infrared spectroscopy ofmono-and divanadium oxide cluster cations. J. Chem. Phys.2004,120:6461-6470.
[217] Yoder B. L., Maze J. T., Raghavachari K., et al. Structures of Mo–2OyandMo2Oy(y=2,3, and4) studied by anion photoelectron spectroscopy anddensity functional theory calculations. J. Chem. Phys.2005,122:094313-1-9.
[218] Fielicke A., Rademann K. Interaction of bismuth oxide cluster cations withalkenes and molecular oxygen: Bi4O6+, a possible reactive center for alkeneoxidation. J. Phys. Chem. A2000,104:6979-6982.
[219] Bienati M., Bona i-Koutecky V., Fantucci P. Theoretical study of the reactivityof bismuth oxide cluster cations with ethene in the presence of molecularoxygen. J. Phys. Chem. A2000,104:6983-6992.
[220] Fujiwara T., Iizuka A., Sato K., et al. Gas phase antimony/tungsten/oxygencluster cations. Int. J. Mass Spectrom.2005,242:57-62.
[221] Jang Y. H., Goddard W. A. III Mechanism of selective oxidation andammoxidation of propene on bismuth molybdates from DFT calculations onmodel clusters. J. Phys. Chem. B2002,106:5997-6013.
[222] Zhai H. J., Huang X., Waters T., et al. Photoelectron spectroscopy of doublyand singly charged group vib dimetalate anions: M2O72-, MM’O72-, and M2O7-(M, M’=Cr, Mo, W). J. Phys. Chem. A2005,109:10512-10520.
[223] Huang X., Zhai H. J., Li J., et al. On the structure and chemical bonding oftri-tungsten oxide clusters W3On-and W3On(n=7-10): W3O8as a potentialmolecular model for o-deficient defect sites intungsten oxides. J. Phys. Chem. A2006,110:85-92.
[224] Yang X., Waters T., Wang X. B., et al. Photoelectron spectroscopy of freepolyoxoanions Mo6O192-and W6O192-in the gas phase. J. Phys. Chem. A2004,108:10089-10093.
[225] Li S., Dixon D. A. Molecular and electronic structures, br nsted basicities, andlewis acidities of group VIB transition metal oxide clusters. J. Phys. Chem. A2006,110:6231-6244.
[226] Li S., Dixon D. A. Benchmark calculations on the electron detachment energiesof MO3-and M2O6-(M=Cr, Mo, W). J. Phys. Chem. A2007,111:11908-11921.
[227] Li S., Dixon D. A. Low-lying electronic states of M3O9-and M3O92-(M=Mo,W). J. Phys. Chem. A2007,111:11093-11099.
[228] Li S., Hennigan J. M., Dixon D. A. Accurate thermochemistry for transitionmetal oxide clusters. J. Phys. Chem. A2009,113:7861-7877.
[229] Sun Q., Rao B. K., Jena P., et al. Appearance of bulk properties in smalltungsten oxide clusters. J. Chem. Phys.2004,121:9417-9422.
[230] Bondarchuk O., Huang X., Kim J., et al. Formation of monodisperse (WO3)3clusters on TiO2(110). Angew. Chem.,2006,118,4904-4907.
[231] Waters T., Huang X., Wang X. B., et al. Photoelectron spectroscopy of freemultiply charged keggin anions α-[P12O40]3-(M=Mo, W) in the gas phase. J.Phys. Chem. A,2006,110:10737-10741.
[232] Foresman J. B., Frisch A. E. Exploring chemistry with electronic structuremethods,2nd ed.; Pittsburgh, PA: Gaussian Inc.,1995.
[233] Koffyberg F. P., Dwight K., Wold A. Interband transitions of semiconductingoxides determined from photoelectrolysis spectra. Solid State Commun.1979,30:433-437.