Diphosphastannylenes: Precursors for Phosphorus-Phosphorus Coupling?

The preparation of the secondary phosphane (Ph){C6H3-2,6-(CH2NMe2)2}PH (1), a potentially base-stabilized ligand, and the sterically protected carbaborane-based phosphane (o-CH3C2B10H10)2PH (2) is reported. Reaction of Sn{N(SiMe3)}2 with 1 gives the diphosphastannylene [(Ph){(C6H3-2,6-CH2NMe2)2}P]2Sn (3) in high yield. In contrast, the room-temperature reaction of 2 with Sn{N(SiMe2)}2 does not proceed. By applying elevated temperatures, the heteroleptic amidophosphastannylene {(o-CH3C2B10H10)2P}{(SiMe3)2N}Sn (4) was formed, instead of the expected diphosphastannylene {(o-CH3C2B10H10)2P}2Sn. The thermal decomposition of compounds 3 and 4 was also studied. The thermal decomposition of 3 produced the new phosphorusphosphorus-bonded compound 5, an unprecedented 1,2-diphosphol-type molecule.