化学学报 ›› 1987, Vol. 45 ›› Issue (1): 23-28. 上一篇    下一篇

研究论文

轴向配体对Rh2(OAc)4电子结构和氧化还原电位的影响

胡震山;朱天培   

  1. 中国科学院长春应用化学研究所
  • 发布日期:1987-01-15

Influence of axial ligands on the redox properties and electronic structure of Rh2(OAc)4

HU ZHENSHAN;ZHU TIANPEI   

  • Published:1987-01-15

本文研究了Rh2(OAc)4配合物在14种非水溶剂中的电子吸收光谱和氧化还原行为.在弱σ-给电子配位体(二氯甲烷、二氯乙烷、丙烯碳酸脂、丙酮、四氢呋喃、N,N-二甲基甲酰胺、丁腈、乙腈苯乙腈和硝基甲烷)情况下,Rh2(OAc)4同其形成溶剂化轴向配合物的氧化电位基本不变.然而,当强σ-给电子配体(吡啶、二甲基亚砜、亚磷酸三乙酯和三苯基膦)与Rh2(OAc)4形成轴向配合物时,产物的氧化电位明显地向阴极方向移动.用两种不同的电子构型解释了电化学数据以及Rh2(OAc)4轴向配合物的中性分子和阳离子游离基电子吸收光谱特征.14种溶剂给电子配位能力有如下顺序:二氯甲烷~二氯乙烷<丙烯碳酸脂<丙酮~四氢呋喃

关键词: 电子传递, 波长, 电子结构, 分子轨道理论, 乙酸 P, 双核络合物, 电化学分析, 电子跃迁, 铑络合物, 多元羧酸

The redox behavior and electronic spectra of Rh2(II)(OAc)4 were studied in 14 nonaq. solns. The oxidation potentials of the axial solvation complexes Rh2(OAc)4.L2 for weak s-donor ligands (L) such as CH2Cl2, (CH2Cl)2, propylene carbonate (PC), MeCN(AN), THF, DMF, PrCN, acetone (AC), PhCN, and MeNO2 are essentially invariant. Observable cathodic shifts of the oxidation potentials occur for the stronger s-donor ligands such as pyridine (Py), DMSO, P(OEt)3 and PPh3. This is explained in terms of 2 types of electronic configuration. Based on these electrochem. and spectra data of the neutral and cation radical of Rh2(OAc)4.L2, the HOMO orbital of Rh2(OAc)4.L2 was confirmed experimental to be dRhRh* in the weak s-donor ligands. In axial Rh2(OAc)4 complexes with stronger s-donor ligands, the HOMO orbital is considered to be sRhRh-L,* which has an electronic transition in the electronic absorption spectra (n1) and electron-transfer in the electrochem. oxidation of the Rh2(OAc).L2. This differs from the case in the weak s-donor ligands, in which n1 results from pRhRh* ?sRhRh* electronic transition, and an electron is removed from the HOMO dRhRh* in electrochem. oxidation The donor power of these solvents is in the order: CH2Cl2~(CH2Cl)2

Key words: ELECTRON TRANSFER, WAVE LENGTH, ELECTRONIC STRUCTURE, MOLECULAR ORBITAL THEORY, ACETIC ACID P, DINUCLEAR COMPLEX, ELECTROCHEMICAL ANALYSIS, ELECTRON TRANSITION, RHODIUM COMPLEX, POLYCARBOXYLIC ACID

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