Studies of the Structures and Bonding of Gold-Bridged Dirhenium Carbonyl Cluster Complexes
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- 作者：Richard D. Adams ; Yuen Onn Wong ; Qiang Zhang
- 刊名：Organometallics
- 出版年：2013
- 出版时间：December 23, 2013
- 年：2013
- 卷：32
- 期：24
- 页码：7540-7546
- 全文大小：565K
- ISSN：1520-6041
文摘
The compounds Re2(CO)8(渭-AuPPh3)2, 1, a dimer of Re(CO)4(渭-AuPPh3), and ax,ax-Re2(CO)8(PPh3)2 were obtained from UV鈥搗is radiation-induced decarbonylation of the compound Re(CO)5[Au(PPh3)]. Compound 1 contains two rhenium atoms bridged by two AuPPh3 groups. The complex has 32 valence electrons and is formally unsaturated by the amount of two electrons. The Re鈥揜e bond distance in 1 is unusually short (Re鈥揜e = 2.9070(3) 脜), as found by a single-crystal structural analysis. The nature of the metal鈥搈etal bonding in 1 was investigated by DFT computational analyses, which have provided evidence not only for 蟽-bonding but also significant complementary 蟺-bonding directly between the two rhenium atoms. The electronic structure of Re2(CO)8(渭-H)2, 2, was similarly analyzed and is compared with that of 1. Compound 1 is intensely colored due to low-energy, metal-based electronic transitions between the HOMO and HOMO-2 and the LUMO. Compound 1 reacts with I2 to yield Re2(CO)8(渭-AuPPh3)(渭-I), 3, and the known compound Re2(CO)8(渭-I)2, 4, by substitution of the bridging AuPPh3 groups with bridging iodide ligands. Compound 3 is electronically saturated, 34 valence electrons, and contains a formal Re鈥揜e single bond: Re鈥揜e = 3.2067(5) 脜. Compound 3 was also in a high yield (83%) from the reaction of Re2(CO)8(渭-H)(渭-CH鈺怌HC4H9) with Au(PPh3)I. The Re鈥揜e bonding in compounds 3, 4, and Re2(CO)10 was also analyzed computationally, and this bonding was compared with their bonding in 1 and 2.