Dimetallaborane analogues of the octaboranes of the type Cp2M2B6H10: structural variations with changes in the skeletal electron count

作者：Branzanic Adrian M V; Lupan Alexandru; King R Bruce

来源：Dalton Transactions, 2016, 45(22): 9354-9362.

DOI：10.1039/c6dt00985a

The structures and energetics of the complete series of hydrogen-rich dimetallaboranes Cp2M2B6H10 and Cp-2*M2B6H10 (Cp = eta(5)-C5H5; Cp* = eta(5)-Me5C5; M = Pd, Pt; Rh, Ir; Ru, Os; Re; Mo, W; Ta), including the experimentally known Cp-2*Rh2B6H10 and Cp-2*W2B6H10 (Cp* = eta(5)-Me5C5), have been investigated by density functional theory. The lowest energy structures of the hyperelectronic Cp2M2B6H10 (M = Pd, Pt; Rh, Ir) systems have central M2B6 frameworks with a hexagonal open face similar to the B-8 networks in arachno-B8H14 and nido-B8H12. The two lowest energy structures for Cp2Rh2B6H10 and Cp-2*Rh2B6H10, lying within 1 kcal mol(-1) of energy, differ only in the locations of the bridging hydrogen atoms around the hexagonal hole consistent with the experimentally observed fluxionality of the hydrogen atoms in Cp-2*Rh2B6H10. Most of the lowest energy Cp2M2B6H10 (M = Ru, Os) structures also have a central M2B6 framework similar to B8H12, typically with such additional features as an additional metal-metal bond or a formal metal-metal double bond. A common motif for the low-energy structures of the hypoelectronic Cp2M2B6H10 (M = Re; Mo, W; Ta) systems, including the experimentally known Cp-2*W2B6H10, is a central M2B4 octahedron with its two M2B faces capped by the remaining boron atoms and with four M-B edges bridged by hydrogen atoms. Such structures can also be considered as oblatonido structures derived from the experimentally known 9-vertex oblatocloso Cp-2*Re2B7H7 structure by removal of the unique degree 4 vertex atom.

• 出版日期2016