213409-52-0Relevant academic research and scientific papers
Low-valent ditantalum complex Ta2(μ-BH3)(μ-dmpm)3(η2-BH4)2: First dinuclear compound containing a bridging BH3 group with direct Ta-B bonds
Cotton, F. Albert,Murillo, Carlos A.,Wang, Xiaoping
, p. 9594 - 9599 (2007/10/03)
The reduction of TaCl5 with LiBH4 in the presence of the bidentate ligand bis(dimethylphosphino)-methane, dmpm, produces the novel BH3-bridged ditantalum complex Ta2(μ-BH3)(μ-dmpm)3(η2-BH4)2 (1) and the acid- base adduct dmpm (BH3)2 (2). Two crystalline forms of 1 were obtained, and their structures have been determined by X-ray crystallography. The unique feature of 1 is that the bridging borane is bound only to the ditantalum metal center, forming a simple metallaborane cluster, Ta2B, with averaged Ta-Ta and Ta-B bond distances of 2.7792[5] and 2.307[9]A?, respectively; the averaged Ta-B separation for the axially coordinated BH4- groups, which are bound to the Ta atoms through hydrogen atoms, is ~0.2 A? longer than that of the bound BH3 group. The μ-BH3 group has one exo-hydrogen atom with a B- h(exo) distance of 1.10-[8] A?. The distance between the endo-hydrogen atom and the boron atom is 1.23[8] A?. Each of the two endo-hydrogen atoms is also bound to a Ta atom with the Ta-H distance of 1.98[8] A?. Compound 1 represents the first example of a structurally characterized metallaborane complex containing a μ-BH3 group bringing two metal centers. The structure of the air-stable compound 2 has also been determined; it shows a strong P to B dative bond with the P-B distance of 1.903(4) A?.
