Unprecedented Conversion of a Compound with Metal–Metal Bonding into a Solvated Molecular Wire
Unprecedented Conversion of a Compound with Metal–Metal Bonding into a Solvated Molecular Wire
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具有金属-金属键合的化合物前所未有地转化为溶剂化分子线
DOI：
10.1002/anie.199627721
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发表时间：
1996
影响因子：
--
通讯作者：
K. Dunbar
中科院分区：
文献类型：
--
作者：
Gary M. Finniss;E. Canadell;C. Campana;K. Dunbar
几十年来，一维化合物一直引起化学家和物理学家的兴趣。这种迷恋的一个主要原因是三十多年前提出的理论预测，即1D导体可能表现出高温s~超导电性。最大的一类一维无机化合物是方形平面的d8配合物，它们在固态下形成柱状堆叠。~~]闭壳体系是不良导体，但氧化掺杂导致混合价态导致金属行为的开始，如部分氧化的四氰铂酸盐（POTCPs），通常被称为克罗曼盐。单核Rh ‘化合物在高浓度的溶液和固体状态下也会形成低聚物，但这些化合物的氧化产生具有金属-金属键或单核Rh ’自由基的“二聚体”化合物，如果大体积的配体是空的。bs61虽然不太常见，但混合价的Rh ‘ /Rh ’物质也有文献记载[71]，但除了几个特征明确的例子外，这些物质也是双核的。[sa- 1]从大量可用的数据中可以明显看出，具有金属-金属（MM）键的离散“二聚体”的形成（佩尔斯畸变的极端情况）是过渡金属化学中的一个主要主题。[']这种情况引起了我们对配体在无分子间金属-金属相互作用的非桥接双核化合物结晶趋势中的作用的好奇。缺乏无限MM键链的一个原因可能是配位化合物中使用的典型配体，如羧酸盐、卤化物和磷化物，不能促进金属原子沿轴向的直接接近。彭等人的报告支持了这一理论，平面二亚胺配体稳定了表现出金属-金属和配体-配体相互作用的短低聚物。[8a1]我们推断，给定合适的配体组合，就有可能诱导双核配合物实际“聚合”成无限的金属-金属键阵列。选择具有四键（M= Mo, Tc）、三键（M= Re）和单键（M= Rh）的非桥接化合物[M2 (MeCN)， I4+和[M，（MeCN） lo] 4+进行研究，因为这些分子仅具有小的线性MeCN配体，其空间效应最小。我们的目标是通过一个电子氧化或还原这些抗磁性分子，并阐明由此产生的自由基种类的固态结构。本文报道了该材料的合成、x射线晶体结构分析和能带结构计算
One-dimensional (1 D) compounds have intrigued chemists and physicists for decades.“. A primary reason for this fascination is the theoretical prediction advanced by Little over thirty years ago that 1D conductors may exhibit high-temperature s~ perconductivity.~~~ The largest class of 1D inorganic compounds are square-planar d8 complexes that form columnar stacks in the~ olid-state.~~] The closed-shell systems are poor conductors, but oxidative doping to give a mixed-valence state leads to the onset of metallic behavior as exemplified by the partially oxidized tetracyanoplatinates (POTCPs) often referred to as Krogmann salts.‘4a3 dl Mononuclear Rh’compounds also form oligomers at high concentrations in solution and in the solid state, but oxidation of these compounds yields “dimerized” compounds with metal-metal bonding or mononuclear Rh” radicals if bulky ligands are empl~ yed.‘~”. bs61 Although less common, mixed-valence Rh ‘/Rh” species have been documented,[71 but these are also dinuclear with the exception of several well-characterized examples.[sa-‘1 It is evident from the tremendous body of available data that the formation of discrete “dimers” with metal-metal (MM) bonding (the extreme case of Peierls distortion) is a dominant theme in transition metal chemistry.[’] This situation aroused our curiosity as to the role of the ligands on the tendency for unbridged dinuclear compounds to crystallize without intermolecular metal-metal interactions. One reason for the scarcity of infinite MM bonded chains may be the fact that the typical ligands used in coordination compounds, such as carboxylates, halides, and phosphanes, do not facilitate the direct approach of metal atoms along the axial direction. In support of this theory are the reports by Peng et al., that planar diimine ligands stabilize short oligomers that exhibit both metal-metal and ligandligand interactions.[8a1 We reasoned that, given the proper ligand set, it may be possible to induce a dinuclear complex to actually “polymerize” into an infinite metal-metal bonded array. The unbridged compounds [M2 (MeCN), I4+ and [M,(MeCN) lo] 4+ with quadruple (M= Mo, Tc), triple (M= Re), and single (M= Rh) bonds were chosen for this investigation because these molecules possess only small, linear MeCN ligands whose steric effects are minimal. Our objective was to oxidize or reduce these diamagnetic molecules by one electron and to elucidate the solid-state structures of the resulting radical species. Herein we report the synthesis, X-ray crystal structure analysis, and band structure calculations