Novel η1-allyl– and acyliridium(III)/pybox complexes

The complex [IrCl(η1-CH2CHCH2)(η2-MeO2CCCCO2Me){κ3-N,N,N-(S,S)-iPr-pybox}][PF6] (1) has been prepared by oxidative addition of allyl chloride to a solution of the complex [Ir(η2-MeO2CCCCO2Me)2{κ3-N,N,N-(S,S)-iPr-pybox}][PF6] in acetone. The treatment of the complexes [Ir(η2-C2H4)2(κ3-N,N,N-R-pybox)][PF6] (R-pybox = 2,6-bis[4′-(S)-isopropyloxazolin-2′-yl]pyridine, 2,6-bis[4′-(R)-phenyloxazolin-2′-yl]pyridine) with (E)-3-chloro-1-phenyl-1-propene (cinnamyl chloride) (1:1 molar ratio) in methanol at −40 °C, followed by warming to room temperature, affords stereoselectively the complexes [IrCl(η1-CH2CHCHPh)(η2-C2H4)(κ3-N,N,N-R-pybox)][PF6] (R = (S,S)-iPr (2), (R,R)-Ph (3)). Warming of acetonitrile solutions of complexes 2 or [IrCl(η3-C3H5){κ3-N,N,N-(S,S)-iPr-pybox}][PF6] gives the complexes [IrCl(η1-CH2CHCHPh)(MeCN){κ3-N,N,N-(S,S)-iPr-pybox}][PF6] (4) and [IrCl(η1-CH2CHCH2)(MeCN){κ3-N,N,N-(S,S)-iPr-pybox}][PF6] (5). Complex [Ir(η2-C2H4)2{κ3-N,N,N-(S,S)-iPr-pybox}][PF6] undergoes the oxidative addition of RCOCl (R = Me, Ph) in acetonitrile leading stereoselectively to the complexes [IrCl(COR)(MeCN){κ3-N,N,N-(S,S)-iPr-pybox}][PF6] (R = Me (6), Ph (7)). The structure of the complex 7 · CH2Cl2 has been determined by an X-ray monocrystal study.

The synthesis of enantiopure η1-allyliridium(III) complexes [IrCl(η1-CH2CHCHR)(L)(κ3-N,N,N-iPr-pybox)][PF6] (R = H, L = MeO2CCCCO2Me, MeCN; R = Ph, L = C2H4, MeCN), [IrCl(η1-CH2CHCHPh)(η2-C2H4)(κ3-N,N,N-Ph-pybox)][PF6] is reported. The results suggest that a η1-coordination of allyl group is favoured in the case of DMAD and MeCN ligands. The complexes [IrCl(COR)(MeCN)(κ3-N,N,N-iPr-pybox)][PF6] (R = Me, Ph) are obtained by the stereoselective oxidative addition of acyl chloride to the iridium(I) precursors. The structure of the complex 7 · CH2Cl2 has been determined by an X-ray monocrystal study.Figure optionsDownload as PowerPoint slide