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

Abstract

The new phosphine PBut2(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{PBut2(CHCPh)}]+ forms reversibly and wrth dry hydrogen chloride [PtCl2{PBut2[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]}{PBut2[CHC(OMe)Ph]}]. Infrared, 1H, 31P and some 13C n.m.r. data are given.