title: Interactions of Rh(III)-dihydrido-bis(phosphine) complexes with semicarbazones.
abstract: Interaction of cis,trans,cis-[Rh(H)2(PR3)2(acetone)2]PF6 complexes (R = aryl or R3 = Ph2Me, Ph2Et) under H2 with E-semicarbazones gives the Rh(III)-dihydrido-bis(phosphine)-semicarbazone species cis,trans-[Rh(H)2(PR3)2{R'(R' ')C=N-N(H)CONH2}]PF6, where R' and R' ' are Ph, Et, or Me. The complexes are generally characterized by elemental analysis, 31P{1H} NMR, 1H NMR, and IR spectroscopies, and MS. X-ray analysis of three PPh3 complexes reveals chelation of E-semicarbazones by the imine-N atom and the carbonyl-O atom. In contrast, the corresponding reaction of [Rh(H)2(PPhMe2)2(acetone)2]PF6 with acetophenone semicarbazone gives the ortho-metalated-semicarbazone species cis-[RhH(PPhMe2)2{o-C6H4(Me)C=N-N(H)CONH2}]PF6. The X-ray structure of E-propiophenone semicarbazone is also reported. Rhodium-catalyzed, homogeneous hydrogenation of semicarbazones was not observed even at 40 atm H2.
authors.affiliation: Department of Chemistry, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada.
authors.forename: Maria B
authors.initials: MB
authors.lastname: Ezhova
authors.forename: Brian O
authors.initials: BO
authors.lastname: Patrick
authors.forename: Kapila N
authors.initials: KN
authors.lastname: Sereviratne
authors.forename: Brian R
authors.initials: BR
authors.lastname: James
authors.forename: Francis J
authors.initials: FJ
authors.lastname: Waller
authors.forename: Michael E
authors.initials: ME
authors.lastname: Ford