Effect of electron count on the structures of (benzene)metallaboranes with 9-12 vertices: Comparison of the iron and ruthenium systems

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• 作者：R. Bruce King^a ; ^{rbking@chem.uga.edu} ; Ioan Silaghi-Dumitrescu^b ; ¹ ; Ioana 艦ovago^b
• 关键词：Iron ; Ruthenium ; Metallaboranes ; Polyhedra ; Density functional theory ; Benzene metal complexes
• 刊名：Polyhedron
• 出版年：2012
• 期刊代码：87_02775387
• 类别：ch
• 出版时间：19 June, 2012
• 卷：40
• 期：1
• 页码：110-117
• 文件大小：1346 K

摘要

The metallaboranes (C₆H₆)MB_n鈭?H_n鈭?^z (n = 9, 10, 11, 12; z = 鈭?, 0, +2; M = Fe, Ru) have been studied by density functional theory. The most spherical closo deltahedral structures were found as global minima in the dianions (畏⁶-C₆H₆)MB_n鈭?H_n鈭?^{2鈭?/sup> in accord with the Wade-Mingos rules for these 2n + 2 skeletal electron systems. However, novel alternative low energy 鈥渟lipped鈥?structures were found for (畏4-C₆H₆)MB₉H₉2鈭?/sup> with a tetrahapto rather than hexahapto benzene ring and the 10-vertex isocloso deltahedron with the metal atom at the unique degree 6 vertex. The expected isocloso structures were found for the neutral 10 and 11 vertex systems (畏6-C₆H₆)MB_n鈭?H _n鈭? (M = Fe, Ru; n = 10, 11) with the metal at the unique degree 6 vertex in accord with their 2n skeletal electrons. Similar non-icosahedral 12-vertex (畏6-C₆H₆)MB₁₁H₁₁ (M = Fe, Ru) structures with the iron or ruthenium at a degree 6 vertex were found to be of lower energy than the corresponding icosahedral structures. For the 9-vertex (畏6-C₆H₆)MB₈H₈ (M = Fe, Ru) the closo tricapped trigonal prism structure with the metal at a degree 5 vertex is predicted to be of lower energy than the isocloso structure with the metal at a degree 6 vertex. Capped isocloso structures with the metal at a unique degree 7 vertex are predicted for the lowest energy structures of the dications (畏6-C₆H₆)MB_n鈭?H_n鈭?2+ (n = 10, 11; M = Fe, Ru). A related bicapped pentagonal bipyramid structure with the iron at a unique degree 7 vertex is found for the 9-vertex ferraborane dication (畏6-C₆H₆)FeB₈H₈2+. The isocloso and capped isocloso structures with the metal atoms at degree 6 and 7 vertices, respectively, for the 2n skeletal electron (畏6-C₆H₆)MB_n鈭?H_n鈭? and 2n 鈭?#xA0;2 skeletal electron (畏6-C₆H₆)MB_n鈭?H_n鈭?2+, respectively, appear to be more favorable for the ruthenium species (M = Ru) than for the corresponding iron species (M = Fe).}