Chemistry of Phosphine–Borane Adducts at Platinum Centers: Synthesis and Reactivity of PtIIComplexes with Phosphinoborane Ligands

Reaction of [Pt(PEt3)3] with the primary and secondary phosphine–borane adducts PhRPH⋅BH3(R=H, Ph) resulted in oxidative addition of a PH bond at the Pt0center to afford the complexes trans‐[PtH(PPhR⋅BH3)(PEt3)2] (1: R=H; 2: R=Ph). The products 1and 2were characterized by 1H, 11B, 13C, 31P, and 195Pt NMR spectroscopy, and the molecular structures were verified by X‐ray crystallography. In both cases, a transarrangement of the hydride ligand with respect to the phosphidoborane ligand was observed. When 2was treated with PhPH2⋅BH3, a novel phosphidoborane ligand‐exchange reaction occurred which yielded 1and Ph2PH⋅BH3. Treatment of 2with one equivalent of depe (depe=1,2‐bis(diethylphosphino)ethane) resulted in the formation of the complex cis‐[PtH(PPh2⋅BH3)(depe)] (3), in which the hydride ligand and the phosphidoborane ligand are in a cisarrangement. Treatment of 3with PhPH2⋅BH3was found to result in an exchange of the phosphidoborane ligands to give the complex cis‐[PtH(PPhH⋅BH3)(depe)] (4) and Ph2PH⋅BH3. Complex 4was found to undergo further reaction in the presence of PhPH2⋅BH3to give meso‐cis‐[Pt(PPhH⋅BH3)2(depe)] (5) and rac‐cis‐[Pt(PPhH⋅BH3)2(depe)] (6).