Multinuclear NMR study of PH2P(BH3)Li in THF-d8 solution: new aspects on the reactivity of P-alkylation and reduction reactions

P-chiral phosphide-boranes have been shown to be valuable building blocks in the synthesis of enantiomerically pure phosphines with chirogenic phosphorus centers.1 However, despite the considerable interest towards these compounds no information about their structure and their stability in solution is present in the literature. For this reason a set of heteronuclear (1H, 6Li, 11B, 13C and 31P) NMR experiments in THF-d8 has been conducted on a lithium borylphosphide model: lithium diphenylphosphide borane 1 (Figure 1). These experiments have clearly established that the deprotonation of diphenylphosphine-borane by n-BuLi in THF leads to a disolvated monomer with the lithium cation connected to the hydrides on the boron and two THF molecules. These structural data allowed us also to understand some aspects of its reactivity in the field of P-alkylation and reduction reactions of carbonyl species