The preparation of platinum(II) complexes with an ortho-metallated carbene ligand: the X-ray and molecular structure of [Pt{C(NHC6H4CH3)(NHC6H3CH3)}{PPh2(CH2)2PPh2}]ClO4

Treatment of PtCl(CNR)(acac) (R = p-tolyl; acac = acetylacetonate) with p-toluidine gives the carbene compound PtCl{C(NHR) 2 }(acac). Reaction of this complex with a silver salt, followed by treatment with a neutral ligand L, gave ortho-metallated species [Pt{C(NHC 6 H 4 CH3)(NHC 6 H 3 CH 3 )}L 2 ] + which have been isolated as crystalline salts. The molecular structure of the ClO 4 − salt with L 2 = bisdiphenylphosphinoethane has been determined by X-ray diffraction. Crystals are monoclinic, space group P2 1 /n, with four formula units in a cell of dimensions a = 20.370(3), b = 18.116(3), c = 10.770(2) Ǻ, and β = 99.47(6)°. Full matrix least-squares refinement on F using 3252 observations gave a conventional agreement factor R. = 0.047. While the formation of these ortho-metallated carbene complexes restricts the further extension of this chemistry, the ready reversal by acid treatment is unusual.