Expanding the allyl analogy: accessing η3-P,B,P diphosphinoborane complexes of group 10

Abstract

Using the diphosphinoborane, (PPh₂)₂BMes (Mes = 2,4,6-Me₃C₆H₃), we report the first examples of η³-P,B,P-ligated complexes using Ni(0) and Pt(ii). Reaction of (PPh₂)₂BMes with Ni(COD)₂ or Pt(COD)Me₂ (COD = 1,5-cyclooctadiene) results in gradual COD displacement to give [η³-P,B,P-(PPh₂)₂BMes]Ni(COD) (3) or [η³-P,B,P-(PPh₂)₂BMes]Pt(CH₃)₂ (6). Complex 3 serves as a versatile Ni-containing synthon for the preparation of square planar or tetrahedral Ni(0) complexes. Notably, the M-B interaction in these systems is non-negligible - with coordination resulting in an upfield shift of ca. 80 ppm in the ¹¹B NMR spectrum. We also show that treatment of the Pt^IV halide precursor, [PtMe₃I]₄ with this ligand framework results in migration of X-type ligands (CH₃^- and I^-) to boron and reductive elimination of ethane (C₂H₆) to give a distorted square planar zwitterionic Pt^II complex, Pt[κ²-P,P-(PPh₂)₂B(Mes)(CH₃)][κ²-P,P-(PPh₂)₂B(Mes)(I)] (10). This reactivity suggests the feasibility of (PPh₂)₂BMes-ligand-induced labilization of M-X ligands.