Homoleptic Metal Carbonyl Cations of the Electron‐Rich Metals: Their Generation in Superacid Media Together with Their Spectroscopic and Structural Characterization
Homoleptic Metal Carbonyl Cations of the Electron‐Rich Metals: Their Generation in Superacid Media Together with Their Spectroscopic and Structural Characterization
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DOI：
10.1002/anie.199724021
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发表时间：
1997-12
影响因子：
--
通讯作者：
H. Willner;F. Aubke
中科院分区：
文献类型：
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作者：
H. Willner;F. Aubke
第8族至第12族富电子金属的均配羰基阳离子是过渡金属羰基化合物大家族的最新成员。它们可以在几个方面与典型的金属羰基络合物区分开。它们的合成需要在诸如氟硫酸和“魔酸”HSO 3F·SbF 5等超强酸中进行金属盐的羰基化。以五氟化锑为反应介质，得到以[Sb 2F 11]−为抗衡离子的热稳定盐。[Sb 2F 11]−阴离子和超强酸反应介质以前在d-区元素的有机金属化学中几乎没有应用。在金属羰基化学中也是前所未有的是阳离子的配位数为4（正方形平面配位）和2（线性配位）的配位几何结构。金属的形式氧化态和络合阳离子的电荷从+1延伸到+3：因此CO主要以σ-键合到金属上，并且CO键强烈极化。最小的金属→ CO π-背键和碳上的正部分电荷表现在长M C键，短C O键，高频率的C O伸缩振动（高达2300 cm−1）和小的13 C NMR化学位移（高达δc = 121）。这些不寻常的同配位羰基阳离子的突出例子，最近在这本杂志上的一个亮点的主题，包括第一个羰基阳离子的p-块金属[Hg（CO）2]2+，第一个三价羰基阳离子[Ir（CO）6]3+，和第一个多电荷羰基阳离子的3d金属[Fe（CO）6]2+。在这篇综述中，我们提出：（a）概述了羰基金属阳离子的历史起源及其合成方法;（B）概述了羰基阳离子的一般领域，这是在一个非常短的时间内发展起来的;（c）讨论了金属-CO键合的结构和光谱特征;（d）讨论了与反应介质和[Sb 2F 11]−阴离子有关的特殊意义;（e）讨论了[Sb 2F 11]−阴离子的化学性质。及（e）指出最近的成果及预期的未来发展。
Homoleptic carbonyl cations of the electron‐rich metals in Groups 8 through 12 are the newest members of the large family of transition metal carbonyls. They can be distinguished from typical metal carbonyl complexes in several respects. Their synthesis entails carbonylation of metal salts in such superacids as fluorosulfuric acid and “magic acid” HSO3FSbF5. Thermally stable salts with [Sb2F11]−as counterion are obtained with antimony pentafluoride as reaction medium. Both the [Sb2F11]−anion and superacid reaction media have previously found little application in the organometallic chemistry of d‐block elements. Also unprecedented in metal carbonyl chemistry are the coordination geometries with coordination numbers 4 (square‐planar coordination) and 2 (linear coordination) for the cation. Formal oxidation states of the metals, and the charges of the complex cations, extend from + 1 to +3: thus CO is largely σ‐bonded to the metal, and the CO bond is strongly polarized. Minimal metal → CO π‐backbonding and a positive partial charge on carbon are manifested in long MC bonds, short CO bonds, high frequencies for CO stretching vibrations (up to 2300 cm−1), and small13C NMR chemical shifts (up to δc, = 121). Prominent examples of these unusual homoleptic carbonyl cations, which were recently the subject of a Highlight in this journal, include the first carbonyl cation of a p‐block metal [Hg(CO)2]2+, the first trivalent carbonyl cation [Ir(CO)6]3+, and the first multiply charged carbonyl cation of a 3d metal [Fe(CO)6]2+. In this overview we propose to (a) outline the historical origins of cationic metal carbonyls and their methods of synthesis; (b) present a summary of the general field of carbonyl cations, which has developed over a yery short period of time; (c) discuss the structural and spectroscopic characteritics of metal–CO bonding; (d) discuss the special significance associated with reaction media and the [Sb2F11]−anion; and (e) point to the most recent results and anticipated future developments.