Phosphane‐Borane Chemistry. – Borane Adducts of Two Polyfunctional Phosphanes

The tris(borane) adduct MeC(CH 2 PMe 2 BH 3 ) 3 ( 2 ) of 1,1,1‐tris‐[(dimethylphosphino)methyl]ethane has been prepared from the tripodal phosphane and Me 2 S–BH 3 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 C 3 symmetry and an overall staggered conformation. In an analogous way the bis(borane) adduct CH 2 (PH 2 BH 3 ) 2 ( 3 ) of 1,3‐diphosphapropane has been synthesized, which decomposes above 50°C to give insoluble products, whose elemental analysis indicated that termal P–C bond cleavage is more frequent than P–B bond cleavage.