Structural, electrochemical, and magnetic properties of a four-membered redox series ([Cr(L3)]n-, n = 0-3) in catechol-benzoquinone complexes of chromium
Structural, electrochemical, and magnetic properties of a four-membered redox series ([Cr(L3)]n-, n = 0-3) in catechol-benzoquinone complexes of chromium
复制标题
铬儿茶酚苯醌配合物中四元氧化还原系列 ([Cr(L3)]n-, n = 0-3) 的结构、电化学和磁性
DOI：
10.1021/ic50192a006
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发表时间：
1979
期刊：
影响因子：
--
通讯作者：
K. Raymond
中科院分区：
文献类型：
--
作者：
S. R. Sofen;D. Ware;S. Cooper;K. Raymond
The complexes tris (3, 5-di-iert-butyl-o-benzoquinone) chromium (0) and potassium tris (3, 5-dwerr-butylcatecholato) chromate (III) have been isolated. Electrochemical techniques have demonstrated these complexes to be members of a reversible three-electron redox series with formal reduction potentials of+ 0.03,-0.47, and-0.89 V vs. SCE in acetonitrile. The four members of this series have been characterized by visible, infrared, and EPR spectroscopies as well as by cyclic voltammetry and magnetic susceptibility. From 4.3 to 298 K the neutral complex is diamagnetic. The mono-, di-, and trianion have, respectively, 1, 2, and 3 unpaired electrons. The EPR spectrum of the monoanion consists of a signal centered at g= 1.98 with 8-G line width and coupling to themetal of 24.3 G. The neutral complex has spontaneously resolved upon crystallization to the A-cis isomer inspace group R3 with a= 16.385 (3) Á, c= 13.874 (4) Á, rf (exptl)= 1.08 g cm" 3, andd (calcd)= 1.11 g cm" 3 for Z= 3. The crystallographic symmetry of the molecule is C3 while the symmetry of the coordination polyhedron is Z) 3. The ligand structure in the neutral complex retains significant quinone character; the C-0 bond length is 1.285 (8) Á and there is an alternation in the CC bond lengths of the ring which range from 1.370 (10) to 1.433 (9) Á. The Cr-0 bond length is 1.933 (5) Á. The structural results are compared to those of the trianion, tris (catecholato) chromate (III), in which the ligand retains an undistorted catechol geometry.
