PHOSPHANE-BORANE CHEMISTRY - BORANE ADDUCTS OF 2 POLYFUNCTIONAL PHOSPHANES

The tris(borane) adduct MeC(CH2PMe2BH3)3 (2) of 1,1,1-tris[(dimethylphosphino)methyl]ethane has been prepared from the tripodal phosphane and Me2S-BH3 as the borane source. The crystal structure of 2.1/2 toluene has been determined by single-crystal X-ray diffraction methods. The molecules display crystallographic C3 symmetry and an overall staggered conformation. In an analogous way the bis(borane) adduct CH2(PH2BH3)2 (3) of 1,3-diphosphapropane has been synthesized, which decomposes above 50-degrees-C to give insoluble products, whose elemental analysis indicated that termal P-C bond cleavage is more frequent than P-B bond cleavage.