| Summary: | A multinuclear NMR study shows that the deprotonation of diphenyiphosphine-orane by n-BuLi in THF leads to a disolvated lithium phosphido-borane Ph2P(BH3)Li of which L1 is connected to the hydrides on the boron and two THF molecules rather than to the phosphorus. This entity behaves as both a phosphination and a reducing agent, depending on the kinetic or thermodynamic control imposed to the reaction medium. Density functional theory computations show that H2P(BH3)Li exhibits a ditopic character (the lithium cation can be in the vicinity ot the hydride or of the phosphorus). It explains its dual reactivity (H- or P-addition), both routes going through somewhat similar six- membered transition states with low activation barriers.
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