Contributions to the chemistry of phosphorus .239. On the reaction of diphosphane(4) with diborane(6) and with THF-Borane: Formation of diphosphane-borane, P2H4 center dot BH3, and diphosphane-1,2-bis(borane), BH3 center dot P2H4 center dot BH3

Diphosphane(4) always reacts with diborane(6) in the temperature range of -118 to -78 degrees C, to furnish a mixture of diphosphane-borane, P2H4 . BH3 (1), and diphosphane-1,2-bis(borane), BH3 . P2H4 . BH3 (2), in addition to small amounts of triphosphane-1,3-bis(borane), BH3 . P3H5 . BH3, and phosphane-borane, BH3 . PH3, irrespective of the molar ratios of the reactants employed. The formation of the 1:1 adduct P2H4 . B2H6 reported in the literature [4] could not be confirmed. The structures of compounds 1 and 2 were investigated by nuclear magnetic resonance spectroscopy which revealed the complete, homolytic cleavage of diborane(6). As a result of the bonding of one BH3 group to diphosphane(4), the Lewis basicity of the other PH2 group is markedly reduced. Similar mixtures of products are obtained when the borane adduct THF . BH3 is employed in an analogous reaction. In the case of a 1:1 molar ratio of P2H4:THF . BH3 at -78 degrees C, the reaction furnishes compound 1 exclusively. This product can be isolated in the pure state and is found to be appreciably more stable than diphosphane(4).