Synthesis, Structure, and Reactivity of Dinuclear Nickel Amino-Thiophenolate Complexes Bearing Bridging VO2(OH)2鈥?/sup>and VO2(OR)2鈥?/sup> Coligan
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- 作者：Vasile Lozan ; Jochen Lach ; Berthold Kersting
- 刊名：Inorganic Chemistry
- 出版年：2012
- 出版时间：May 7, 2012
- 年：2012
- 卷：51
- 期：9
- 页码：5213-5223
- 全文大小：515K
- 年卷期：v.51,no.9(May 7, 2012)
- ISSN：1520-510X
文摘
A series of novel mixed ligand dinickel complexes of the type [NiII2L(渭-L鈥?]+, where L鈥?is a tetrahedral oxo-alkoxo vanadate (L鈥?= [O2VV(OR)2]鈭?/sup>, R = H or alkyl) and L a macrocyclic N6S2 supporting ligand, have been prepared, and their esterification reactivity has been studied. The orthovanadate complex [Ni2L(渭-O2V(OH)2)]+ (2), prepared by reaction between [Ni2L(渭-Cl)]ClO4 with Na3VO4 and a phase transfer reagent in CH3CN, reacts smoothly with MeOH and EtOH forming the vanadate diesters [Ni2L(渭-O2V(OMe)2)]+ (3) and [Ni2L(渭-O2V(OEt)2)]+ (4). The dialkyl orthovanadate esters in 3 and 4 are readily transesterified with mono- and difunctional alcohols. Complex 3 can also be generated from 4 by transesterification with MeOH. Complexes 3 and 4 react with diols (ethylene glycol, propylene glycol and diethylene glycol) as well to afford the complexes [Ni2L(渭-O2V(OH)(OCH2CH2OH))]+ (5), [Ni2L(渭-O2V(OCH2)2CH2)]+ (6), and [Ni2L(渭-O2V(OCH2CH2)2O)] (7). The crystal structures of the tetraphenylborate salts of complexes 3鈥?b>7 reveal in each case four-coordinate O2VV(OR)2鈥?/sup> groups bonded in a 渭1,3-bridging mode to generate trinuclear complexes with a central N3Ni(渭-S)2(渭1,3-O2V(OR)2)NiN3 core. The stabilization of the four-coordinate VVO2(OR)2鈥?/sup> moieties is a consequence of both the two-point coordinative fixation to and the steric protection of the bowl-shape binding pocket of the [Ni2L]2+ fragment. Cyclic voltammetry experiments reveal that the encapsulated vanadate esters are not reduced in a potential window of 鈭?.0 to +2.5 V vs SCE. The spins of the nickel(II) (Si = 1 ions) in 3 are weakly ferromagnetically coupled (J = +23 cm鈥?, (H = 鈭?JS1S2)) to produce an S = 2 ground state.