Hypoelectronicity and Chirality in Dimetallaboranes of Group 9 Metals

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• 作者：Szabolcs Jákó ; Alexandru Lupan ; Attila-Zsolt Kun ; R. Bruce King
• 刊名：Inorganic Chemistry
• 出版年：2017
• 出版时间：January 3, 2017
• 年：2017
• 卷：56
• 期：1
• 页码：351-358
• 全文大小：487K
• ISSN：1520-510X

文摘

The structures and energetics of the dimetallaboranes Cp<sub>2sub>M<sub>2sub>B<sub>n–2sub>H<sub>n–2sub> (n = 8, 9, 10, 11, 12; M = Co, Rh, Ir; Cp = η<sup>5sup>-C<sub>5sub>H<sub>5sub>) were studied using density functional theory. The lowest energy Cp<sub>2sub>M<sub>2sub>B<sub>6sub>H<sub>6sub> and Cp<sub>2sub>M<sub>2sub>B<sub>7sub>H<sub>7sub> structures are chiral C<sub>2sub> structures based on the corresponding closo deltahedra, namely the bisdisphenoid and the tricapped trigonal prism. The permethylated iridaboranes Cp*<sub>2sub>Ir<sub>2sub>B<sub>6sub>H<sub>6sub> and Cp*<sub>2sub>Ir<sub>2sub>B<sub>7sub>H<sub>7sub> (Cp* = η<sup>5sup>-Me<sub>5sub>C<sub>5sub>) were synthesized by Ghosh and co-workers. However, they were found by X-ray crystallography to have nondeltahedral structures containing a quadrilateral face, namely a bicapped trigonal prism and a capped square antiprism for the 8- and 9-vertex systems, respectively. These structures correspond to a mean of the two opposite enantiomers and can also represent the “square” intermediate in the interconversion of the two enantiomers. The lowest energy structures for the 10-vertex Cp<sub>2sub>M<sub>2sub>B<sub>8sub>H<sub>8sub> systems are two isocloso deltahedra with one metal atom at a degree 6 vertex and the other metal atom at a degree 5 vertex. Both isomers have been realized experimentally for Cp<sub>2sub>Ir<sub>2sub>B<sub>8sub>H<sub>8sub>. The lowest energy structures for the 11-vertex Cp<sub>2sub>M<sub>2sub>B<sub>9sub>H<sub>9sub> systems have central closo/isocloso deltahedra with one metal atom at a degree 6 vertex and the other metal atom at a nonadjacent degree 5 vertex. This structure type has been found experimentally in both the rhodaboranes and iridaboranes Cp*<sub>2sub>M<sub>2sub>B<sub>9sub>H<sub>9sub> (M = Rh, Ir). The lowest energy structures for the 12-vertex systems Cp<sub>2sub>M<sub>2sub>B<sub>10sub>H<sub>10sub> (M = Co, Rh, Ir) are deltahedra with two adjacent degree 6 vertices for the metal atoms. This type of structure is found experimentally in the rhodium complexes Cp*<sub>2sub>Rh<sub>2sub>B<sub>10sub>H<sub>10–nsub>(OH)<sub>nsub> (n = 1, 2).