Interaction of rhodium(I) bisphosphine complexes with semicarbazones to give orthometallated rhodium(III) complexes

摘要

Interaction of the cis-[Rh(PR_3)_2(Solv)_2]PF_6 complexes (R=Ar or R_3=Ph_2Me,Solv-solvent) under Ar with semicarbazones bearing a phenyl group on the imine-C atom gives the rhodium(III)-hydrido-bis(phosphine)-orthometallated semicarbazone species [RhH(PR_3)_2{(o-C_6H_4(R')C=N-N(H)CONH_2}]PF_6 (R'=Me or Et),which are characterized generally by elemental analysis,~(31)P{~1H} and ~1H NMR spectroscopy,and mass-spectrometry.The PPh_3-containing complex with R'=Me,structurally characterized by X-ray analysis,reveals coordination of the semicarbazone by the ortho-C atom,the imine-N atom,and the amide-carbonyl group.For a semicarbazone containing no Ph group,the rhodium(I) complex [Rh(PR_3)_2(Et(Me)C=N-N(H)CONH_2)]PF_6,containing the eta~2-semicarbazone bonded via the imine-N and carbonyl,is formed.Attempts to hydrogenate the C=N moiety in the complexes or to catalytically hydrogenate the semicarbazones were unsuccessful.