Platinum Complexes of a Borane‐Appended Analogue of 1,1′‐Bis(diphenylphosphino)ferrocene: Flexible Borane Coordination Modes and in situ Vinylborane Formation

A bis(phosphine)borane ambiphilic ligand, [Fe(η 5 ‐C 5 H 4 PPh 2 )(η 5 ‐C 5 H 4 P t Bu{C 6 H 4 (BPh 2 )‐ ortho })] (FcPPB), in which the borane occupies a terminal position, was prepared. Reaction of FcPPB with tris(norbornene)platinum(0) provided [Pt(FcPPB)] ( 1 ) in which the arylborane is η 3 BCC ‐coordinated. Subsequent reaction with CO and CNXyl (Xyl=2,6‐dimethylphenyl) afforded [PtL(FcPPB)] {L=CO ( 2 ) and CNXyl ( 3 )} featuring η 2 BC ‐ and η 1 B ‐arylborane coordination modes, respectively. Reaction of 1 or 2 with H 2 yielded [PtH(μ‐H)(FcPPB)] in which the borane is bound to a hydride ligand on platinum. Addition of PhC 2 H to [Pt(FcPPB)] afforded [Pt(C 2 Ph)(μ‐H)(FcPPB)] ( 5 ), which rapidly converted to [Pt(FcPPB′)] ( 6 ; FcPPB′=[Fe(η 5 ‐C 5 H 4 PPh 2 )(η 5 ‐C 5 H 4 P t Bu{C 6 H 4 (BPh‐CPh=CHPh‐ Z )‐ ortho }]) in which the newly formed vinylborane is η 3 BCC ‐coordinated. Unlike arylborane complex 1 , vinylborane complex 6 does not react with CO, CNXyl, H 2 or HC 2 Ph at room temperature.