Stepwise Cluster Assembly Using VO2(acac) as a Precursor: cis-[VO(OCH(CH3)2)(acac)2], [V2O2(
p://pubs.acs.org/image
详细信息 查看全文
- 作者：Feilong Jiang ; Oren P. Anderson ; Susie M. Miller ; John Chen ; Mohammad Mahroof-Tahir ; and Debbie C. Crans
- 刊名：Inorganic Chemistry
- 出版年：1998
- 出版时间：October 19, 1998
- 年：1998
- 卷：37
- 期：21
- 页码：5439 - 5451
- 全文大小：197K
- 年卷期：v.37,no.21(October 19, 1998)
- ISSN：1520-510X
文摘
The studies of an underexplored synthetic reagent, VO2(acac) (Hacac = acetylacetone) and semirational strategiesfor the formation of a complete series of simple vanadium(V) alkoxide clusters in alcohol-containing solvents.The neutral mono-, di-, tri-, and tetranuclear oxovanadium(V) complexes [V2O2(
-OCH3)2(acac)2(OCH3)2] (1),[V4O4(-O)2(-OCH3)2(3-OCH3)2(acac)2(OCH3)2]·2CH3CN (2), [V4O4(-O)2(-OCH3)2(3-OCH3)2(acac)2(OCH3)2] (3), [V3O3{,-(OCH2)3CCH3}2(acac)2(OR)] (R = CH3 (4), C2H5 (5)), and cis-[VO(OCH(CH3)2)(acac)2](6) with alkoxide and acac- ligands were obtained by reaction of VO2(acac) with a monoalcohol and/or a tridentatealcohol. The structures of complexes 1-3, 5, and 6 were determined by X-ray diffraction methods. Complex 1crystallized in the monoclinic system, P21/n, with a = 7.8668(5) Å, b = 15.1037(9) Å, c = 8.5879(5) Å, 
=106.150(1)
, V = 980.1(1) Å3, Z = 2, and R (wR2) = 0.040 (0.121). Complex 2 crystallized in the monoclinicsystem, P21/n, with a = 8.531(2) Å, b = 14.703(3) Å, c = 12.574(2) Å, = 95.95(2), V = 1568.7(5) Å3, Z =2, and R (wR2) = 0.052 (0.127). Complex 3 crystallized in the triclinic system, P
, with a = 8.5100(8) Å, b =8.9714(8) Å, c = 10.3708(10) Å, 
pha.gif" BORDER=0> = 110.761(1), = 103.104(1), 
= 100.155(1), V = 691.85(11) Å3, Z =1, and R (wR2) = 0.040 (0.105). Complex 5 crystallized in the monoclinic system, P21/n, with a = 14.019(2)Å, b = 11.171(2) Å, c = 19.447(3) Å, = 109.18(1), V = 2876.5(8) Å3, Z = 4, and R (wR2) = 0.062 (0.157).Complex 6 crystallized in the monoclinic system, P21/n, with a = 15.0023(8) Å, b = 8.1368(1) Å, c = 26.5598(2) Å, = 95.744(1), V = 3225.89(8) Å3, Z = 8, and R (wR2) = 0.060 (0.154). Complex 1 is a discrete,centrosymmetric dimer in which two vanadium atoms are bridged by two methoxide ligands. Compound 2 containsa V4O4 eight-membered ring with both -oxo and -alkoxo bridging ligands; the ring is capped above and belowby two triply bridging methoxo ligands. Compound 3 has the same structure as 2. The three vanadium atomsin complex 5 are linked by four bridging oxygen atoms from two tridentate thme3- ligands to form a V3O4 chainin which V-O bonds alternate in length. The V-O(isopropoxo) bond in 6 is cis to V=O, and the V-O(acac)bond trans to the oxo group is relatively long. The V2O2 rings of complex 1 and the mononuclear 1:2 complexcan be considered to be the basic building block of the trinuclear complexes 4 and 5 and the tetranuclear complex2, acting to extend the vanadium-oxide framework. 51V and 1H NMR spectroscopic studies of the solution stateof complexes 1-6 revealed dramatic differences in structural and hydrolytic stability of these complexes.Compounds 1 and 3 only remained intact at low temperature in CDCl3 solution, whereas the mononuclear compound6 could remain at ambient temperature for ~10 h. Compound 4 only maintained its solid-state structure at lowtemperature in CDCl3 solution, whereas compound 5 was significantly more stable. The structural integrity ofoligomeric vanadium-oxygen frameworks increased significantly when the coordinating alkoxide group showedmore resistance to exchange reactions than the methoxide group. The solid state and solution properties of thisnew group of complexes not only testify to the versatility of VO2(acac) as a vanadium(V) precursor but also raisequestions relating to solution structure and properties of related vanadium complexes with insulin-mimetic propertiesand catalytic properties.
-OCH3)2(acac)2(OCH3)2] (1),[V4O4(-O)2(-OCH3)2(3-OCH3)2(acac)2(OCH3)2]·2CH3CN (2), [V4O4(-O)2(-OCH3)2(3-OCH3)2(acac)2(OCH3)2] (3), [V3O3{,-(OCH2)3CCH3}2(acac)2(OR)] (R = CH3 (4), C2H5 (5)), and cis-[VO(OCH(CH3)2)(acac)2](6) with alkoxide and acac- ligands were obtained by reaction of VO2(acac) with a monoalcohol and/or a tridentatealcohol. The structures of complexes 1-3, 5, and 6 were determined by X-ray diffraction methods. Complex 1crystallized in the monoclinic system, P21/n, with a = 7.8668(5) Å, b = 15.1037(9) Å, c = 8.5879(5) Å, =106.150(1), V = 980.1(1) Å3, Z = 2, and R (wR2) = 0.040 (0.121). Complex 2 crystallized in the monoclinicsystem, P21/n, with a = 8.531(2) Å, b = 14.703(3) Å, c = 12.574(2) Å, = 95.95(2), V = 1568.7(5) Å3, Z =2, and R (wR2) = 0.052 (0.127). Complex 3 crystallized in the triclinic system, P, with a = 8.5100(8) Å, b =8.9714(8) Å, c = 10.3708(10) Å, pha.gif" BORDER=0> = 110.761(1), = 103.104(1), = 100.155(1), V = 691.85(11) Å3, Z =1, and R (wR2) = 0.040 (0.105). Complex 5 crystallized in the monoclinic system, P21/n, with a = 14.019(2)Å, b = 11.171(2) Å, c = 19.447(3) Å, = 109.18(1), V = 2876.5(8) Å3, Z = 4, and R (wR2) = 0.062 (0.157).Complex 6 crystallized in the monoclinic system, P21/n, with a = 15.0023(8) Å, b = 8.1368(1) Å, c = 26.5598(2) Å, = 95.744(1), V = 3225.89(8) Å3, Z = 8, and R (wR2) = 0.060 (0.154). Complex 1 is a discrete,centrosymmetric dimer in which two vanadium atoms are bridged by two methoxide ligands. Compound 2 containsa V4O4 eight-membered ring with both -oxo and -alkoxo bridging ligands; the ring is capped above and belowby two triply bridging methoxo ligands. Compound 3 has the same structure as 2. The three vanadium atomsin complex 5 are linked by four bridging oxygen atoms from two tridentate thme3- ligands to form a V3O4 chainin which V-O bonds alternate in length. The V-O(isopropoxo) bond in 6 is cis to V=O, and the V-O(acac)bond trans to the oxo group is relatively long. The V2O2 rings of complex 1 and the mononuclear 1:2 complexcan be considered to be the basic building block of the trinuclear complexes 4 and 5 and the tetranuclear complex2, acting to extend the vanadium-oxide framework. 51V and 1H NMR spectroscopic studies of the solution stateof complexes 1-6 revealed dramatic differences in structural and hydrolytic stability of these complexes.Compounds 1 and 3 only remained intact at low temperature in CDCl3 solution, whereas the mononuclear compound6 could remain at ambient temperature for ~10 h. Compound 4 only maintained its solid-state structure at lowtemperature in CDCl3 solution, whereas compound 5 was significantly more stable. The structural integrity ofoligomeric vanadium-oxygen frameworks increased significantly when the coordinating alkoxide group showedmore resistance to exchange reactions than the methoxide group. The solid state and solution properties of thisnew group of complexes not only testify to the versatility of VO2(acac) as a vanadium(V) precursor but also raisequestions relating to solution structure and properties of related vanadium complexes with insulin-mimetic propertiesand catalytic properties.