A (Diborole)cobalt Complex with a C-H center dot center dot center dot B Bridge, CpCo(1,3-C3B2Me5H), and Its Thallium Derivative: Synthesis, Structure, and Bonding

作者：Muratov Dmitry V; Romanov Alexander S; Petrovskii Pavel V; Antipin Mikhail Yu; Siebert Walter; Kudinov Alexander R^*

来源：European Journal of Inorganic Chemistry, 2012, (26): 4174-4182.

DOI：10.1002/ejic.201200215

• Boron heterocycles
• Cobalt
• Sandwich complexes
• Thallium

The reaction of CpCo(1,3-C3B2Me5H) (1) with CpTl affords the thallium derivative CpCo(1,3-C3B2Me5)Tl (2). The structures of 1 and 2 were determined by X-ray diffraction at 100 K. An extra hydrogen atom in 1 occupies a C-H center dot center dot center dot B bridging position. According to DFT calculations, 1 exists as a mixture of two enantiomers with an enantiomerization barrier of only 0.5 kcal?mol1. The transition state has Cs symmetry with an endo-CH hydrogen atom. The isomeric iso-1with the C-H center dot center dot center dot B bridge is less stable than 1 by 10 kcal?mol1.The formation of 1 and iso-1 from C3B2Me5H and CpCo(C2H4)2 have almost equal activation energies. The isomerization of iso-1 to 1 was shown to proceed as a two-step hydrogen transfer. The bonding of the extra hydrogen atom in the related CHB-bridged carborane nido-2,3,5-C3B3R5H2 and metallacarboranes M(C5R5)(C3B2R'5H) (R, R' = H, Me; M = Co, Rh, Ir) as well as their hydridic isomers MH(C5R5)(C3B2R'5) was compared. According to energy decomposition analysis, the bonding of the parent anion [CpCo(1,3-C3B2H5)] with metal cations becomes stronger in the following order: K+ < Na+ < Tl+ < Li+ < [RuCp]+. The attractive interactions between the [CpCo(1,3-C3B2H5)] and Tl+ fragments are 68?% electrostatic and 32?% covalent.

• 出版日期2012-9