Synthesis and Characterization of O,N-Chelated Vanadium(IV) Oxo Phenolate Complexes: Electronic Effect of Meta and Para Substituents on the Vanadium Center
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- 作者：Henk Hagen ; Antonio Barbon ; Ernst E. van Faassen ; Bert T. G. Lutz ; Jaap Boersma ; Anthony L. Spek ; and Gerard van Koten
- 刊名：Inorganic Chemistry
- 出版年：1999
- 出版时间：September 6, 1999
- 年：1999
- 卷：38
- 期：18
- 页码：4079 - 4086
- 全文大小：135K
- 年卷期：v.38,no.18(September 6, 1999)
- ISSN：1520-510X
文摘
A series of O,N-chelated vanadium(IV) oxo bis(phenolate) complexes (1a-i) have been prepared from [VOCl2(THF)2] and several ortho-amino-functionalized phenols in the presence of a base. The intermediates in the synthesisof these compounds are mono(phenolato)vanadate complexes, as was shown by the reaction of [VOCl2(THF)2]with 1 equiv of HOC6H2(CH2NMe2)2-2,6-Me-4 in the absence of base. This yielded [VOCl2(OC6H2(CH2NMe2)-2-Me-4-(CH2NHMe2)-6)] (2), in which the second amine function acts as an internal base, assisting in bindingthe formed equivalent of HCl. Complex 2 exists in the solid state as the dichlorovanadate(IV) species with theprotonated amine function forming a three-centered intramolecular hydrogen bridge in which both a chlorideatom and the oxygen atom of the phenolate ligand participate. EPR, UV-vis, and cyclic voltammetry analysis ofthe complexes with meta or para substituents (1a-g) on the aryloxy ring showed the hyperfine coupling constant,the HOMO-LUMO transition, and the oxidation potential, respectively, to be linearly related to the Hammett 
constants of the substituents on the monoanionic aryloxy ring. The oxidation potential shows a large dependence(dEox/d = 170 mV (per phenoxy ligand)) on the Hammett constant. Crystal data: 1a, orthorombic, Pbca, a =9.4321(7) Å, b = 14.1919(14) Å, c = 26.5484(14) Å, V = 3553.8(5), Å3, Z = 8; 2, monoclinic, C2/c, a =17.9977(15) Å, b = 15.7445(9) Å, c = 14.4986(6) Å, 
= 113.206(5)
, V = 3776.0(4) Å3, Z = 4.
constants of the substituents on the monoanionic aryloxy ring. The oxidation potential shows a large dependence(dEox/d = 170 mV (per phenoxy ligand)) on the Hammett constant. Crystal data: 1a, orthorombic, Pbca, a =9.4321(7) Å, b = 14.1919(14) Å, c = 26.5484(14) Å, V = 3553.8(5), Å3, Z = 8; 2, monoclinic, C2/c, a =17.9977(15) Å, b = 15.7445(9) Å, c = 14.4986(6) Å, = 113.206(5), V = 3776.0(4) Å3, Z = 4.