Expanding the allyl analogy: accessing η3-PBP diphosphinoborane complexes of group 10

摘要

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.