Tetra- and Dinuclear Nickel(II)-Vanadium(IV/V) Heterometal Complexes of a Phenol-Based N2O2 Ligand: Synthesis, Structures, and Magnetic and Redox Properties
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- 作者：Debdas Mandal ; Pabitra Baran Chatterjee ; Rakesh Ganguly ; Edward R. T. Tiekink ; Rodolphe Clé ; rac ; Muktimoy Chaudhury
- 刊名：Inorganic Chemistry
- 出版年：2008
- 出版时间：January 21, 2008
- 年：2008
- 卷：47
- 期：2
- 页码：584 - 591
- 全文大小：245K
- 年卷期：v.47,no.2(January 21, 2008)
- ISSN：1520-510X
文摘
The tetra- and binuclear heterometallic complexes of nickel(II)-vanadium(IV/V) combinations involving a phenol-based primary ligand, viz., N,N'-dimethyl-N,N'-bis(2-hydroxy-3,5-dimethylbenzyl)ethylenediamine (H2L1), are reportedin this work. Carboxylates and 
-diketonates have been used as ancillary ligands to obtain the tetranuclear complexes[NiII2VV2(RCOO)2(L1)2O4] (R = Ph, 1; R = Me3C, 2) and the binuclear types [(-diket)NiIIL1VIVO(-diket)] (3 and 4),respectively. X-ray crystallography shows that the tetranuclear complexes are constructed about an unprecedentedheterometallic eight-membered Ni2V2O4 core in which the (L1)2- ligands are bound to the Ni center in a N2O2 modeand simultaneously bridge a V atom via the phenoxide O atoms. The cis-N2O4 coordination geometry for Ni iscompleted by an O atom derived from the bridging carboxylate ligand and an oxo O atom. The latter two atoms,along with a terminal oxide group, complete the O5 square-pyramidal coordination geometry for V. Each of thedinuclear compounds, [(acac)NiIIL1VIVO(acac)] (3) and [(dbm)NiIIL1VIVO(dbm)] (4) [Hdbm = dibenzoylmethane], alsofeatures a tetradentate (L1)2- ligand, Ni in an octahedral cis-N2O4 coordination geometry, and V in an O5 square-pyramidal geometry. In 3 and 4, the bridges between the Ni and V atoms are provided by the (L1)2- ligand. TheNi···V separations in the structures lie in the narrow range of 2.9222(4) Å (3) to 2.9637(5) Å (4). The paramagneticNi centers (S = 1) in 1 and 2 are widely separated (Ni···Ni separations are 5.423 and 5.403 Å) by the doubleVVO4 bridge that leads to weak antiferromagnetic interactions (J = -3.6 and -3.9 cm-1) and thus an ST = 0ground state for these systems. In 3 and 4, the interactions between paramagnetic centers (NiII and VIV) are alsoantiferromagnetic (J = -8.9 and -10.0 cm-1), leading to an ST = 1/2 ground state. Compound 4 undergoes twoone-electron redox processes at E1/2 = +0.66 and -1.34 V vs Ag/AgCl reference due to a VIV/V oxidation and aNiII/I reduction, respectively, as indicated by cyclic and differential pulse voltammetry.
-diketonates have been used as ancillary ligands to obtain the tetranuclear complexes[NiII2VV2(RCOO)2(L1)2O4] (R = Ph, 1; R = Me3C, 2) and the binuclear types [(-diket)NiIIL1VIVO(-diket)] (3 and 4),respectively. X-ray crystallography shows that the tetranuclear complexes are constructed about an unprecedentedheterometallic eight-membered Ni2V2O4 core in which the (L1)2- ligands are bound to the Ni center in a N2O2 modeand simultaneously bridge a V atom via the phenoxide O atoms. The cis-N2O4 coordination geometry for Ni iscompleted by an O atom derived from the bridging carboxylate ligand and an oxo O atom. The latter two atoms,along with a terminal oxide group, complete the O5 square-pyramidal coordination geometry for V. Each of thedinuclear compounds, [(acac)NiIIL1VIVO(acac)] (3) and [(dbm)NiIIL1VIVO(dbm)] (4) [Hdbm = dibenzoylmethane], alsofeatures a tetradentate (L1)2- ligand, Ni in an octahedral cis-N2O4 coordination geometry, and V in an O5 square-pyramidal geometry. In 3 and 4, the bridges between the Ni and V atoms are provided by the (L1)2- ligand. TheNi···V separations in the structures lie in the narrow range of 2.9222(4) Å (3) to 2.9637(5) Å (4). The paramagneticNi centers (S = 1) in 1 and 2 are widely separated (Ni···Ni separations are 5.423 and 5.403 Å) by the doubleVVO4 bridge that leads to weak antiferromagnetic interactions (J = -3.6 and -3.9 cm-1) and thus an ST = 0ground state for these systems. In 3 and 4, the interactions between paramagnetic centers (NiII and VIV) are alsoantiferromagnetic (J = -8.9 and -10.0 cm-1), leading to an ST = 1/2 ground state. Compound 4 undergoes twoone-electron redox processes at E1/2 = +0.66 and -1.34 V vs Ag/AgCl reference due to a VIV/V oxidation and aNiII/I reduction, respectively, as indicated by cyclic and differential pulse voltammetry.