Some complexes of platinum, palladium, rhodium, and iridium formed from the bulky ligand (phenylethynyl)di-t-butylphosphine

Abstract

The new phosphine PBu^t₂(CCPh)(L) gives complexes of the type trans-[MX₂L₂](M = Pd or Pt, X = Cl or I) which exist as conformers due to restricted rotation around the phosphorus–metal bonds. The complexes are very resistant to nucleophilic attack but trans-[PtCl₂L₂] can be protonated, e.g., in CF₃CO₂H, [PtCl₂L{PBu^t₂(CHCPh)}]⁺ forms reversibly and wrth dry hydrogen chloride [PtCl₂{PBu^t₂[CHC(Cl)Ph]}₂] is obtained. The complexes cis-[PtMe₂L₂] and trans-[PtCl(Me)L₂] are prepared by displacing cyclo-octa-1,5-diene (cod) from [PtMe₂(cod)], etc., but with 2 mol of L [PtCl₂(cod)] readily gives [PtCl₂(cod)L] in which only one of the cod double bonds is co-ordrnated. The complexes trans-[MCl(CO)L₂](M = Rh or Ir) have also been prepared and the iridium complex converted into [IrHCl₂(CO)L₂] with HCl. With trans-[MCl(CO)L₂] one rotamer is much preferred over the other two. Treatment of H₂IrCl₆ with L gives five-co-ordinate [IrHCl₂L₂] which appears to be trigonal bipyramidal, whereas RhCl₃ gives [RhHCl₂L₂] which is square pyramidal. Treatment of trans-[MCl(CO)L₂](M = Rh or Ir) with sodium propan-2-olate in propan-2-olate in propan-2-ol gives the chelate complexes [[graphic omitted])Ph]}L]. With sodium methoxide in methanol both acetylenic bonds are attacked giving [I[graphic omitted])Ph]}{PBu^t₂[CHC(OMe)Ph]}]. Infrared, ¹H, ³¹P and some ¹³C n.m.r. data are given.