Transition metal-carbon bonds. Part 50. Conversion of mer-[IrCl3-(PMe2R)3](R = Me or Ph) to [IrCl2(CH2PMeR)(PMe2R)2](three-membered ring) by the action of base: crystal structure of [IrCl2(CH2PMePh)(PMe2Ph)2]

Abstract

Treatment of complexes of type mer-[IrCl₃(PMe₂R)₃](R = Ph or Me) with strong bases, LiNPrⁱ₂, LiBuⁿ, or Li(CH₂)₅Li, gives the three-membered ring metallocycles [Ir[graphic omitted]MeR)(PMe₂R)₂], (4a) and (4b), in high yield. Treatment of mer-[IrCl₃{PMe(CH₂Ph)₂}₃] with LiNPrⁱ₂ probably gives a mixture of geometrical and optical isomers [Ir[graphic omitted]HPh)}{PMe(CH₂Ph)₂}₂], (6) and (7). These three-membered ring metallocycles with hydrogen chloride are quantitatively converted back to mer-[IrCl₃(PR₃)₃]. The reaction of complex (4a) with X₂(X = Cl, Br, and I) gives [IrCl₂X(PMe₂Ph)₂(PMePhCH₂X)](8a), (8b), and (8c) respectively. The mer isomer (8a) on irradiation with visible light gives the corresponding fac isomer (9). I.r., ¹H, ¹³C, and ³¹P n.m.r. data are given and discussed. The crystal structure of (4a) has been determined and refined to R 0.047. Cell dimensions are a= 11.619(2), b= 9.248(2), c= 25.498(5)Å, and Z= 4, space group P2₁2₁2₁.