Crystal structures of [IrCl2(NHCHPh)((dppm)(C(N2dppm))-κ3P,C,P′)]Cl·5.5MeCN and [IrI(NHCHPh)(((dppm)C(N2))-κ2P,C)(dppm-κ2P,P′)]I(I3)·0.5I2·MeOH·0.5CH2Cl2: triazene fragmentation in a PCN pincer iridium complex

Abstract

The structure of [IrCl2(C58H51N3P4)]Cl·5.5CH3CN or [IrCl2(NHCHPh)(((dppm)C(N2dppm))-κ3P,C,P)]Cl·5.5CH3CN [3, dppm = bis(diphenylphosphino)methane; systematic name: dichlorido(1,1,3,3,7,7,9,9-octaphenyl-4,5-diaza-1,3λ5,7λ4,9-tetraphosphanona-3,5-dien-6-yl-κ2P1,P9)(phenylmethanimine-κN)iridium(III) chloride acetonitrile hemihendecasolvate], resulting from an oxygen-mediated cleavage of a triazeneylidenephosphorane ligand producing a diazomethylenephosphorane and a nitrene moiety, which in turn rearrange via a Staudinger reaction and a 1,2-hydride shift to the first title complex, involves a six-coordinate IrIII complex cation coordinated by a facial PCP pincer ligand, a benzaldimine and two chlorido ligands. The pincer system features a five- and a seven-membered ring, with the central divalent carbon of the PCP pincer ligand being connected to a phosphine and a diazophosphorane. The chlorido ligands are positioned trans to the central carbon atom and to the phosphorus donor of the seven-membered ring of the pincer system, respectively. A chloride ion serves as counter-ion for the monocationic complex. The structure of [IrI(C26H22N2P2)(C26H22P2)(C6H7N)]I(I3)·0.5I2·CH3OH·0.5CH2Cl2 or [IrI(NHCHPh)((dppm)C(N2)-κ2P,C)(dppm-κ2P,P′)]I(I3)·0.5I2·CH3OH·0.5CH2Cl2 {4, systematic name: (4-diazo-1,1,3,3,-tetraphenyl-1,3λ4-diphosphabutan-4-yl-κP1)iodido[methylenebis(diphenylphosphine)-κ2P,P′](phenylmethanimine-κN)iridium(III) iodide–triiodide–dichloromethane–iodine–methanol (2/2/1/1/2)}, accessed via treatment of the triazeneylidenephosphorane complex [Ir((BnN3)C(dppm)-κ3P,C,N)(dppm-κ2P,P′)]Cl with hydroiodic acid, consists of a dicationic six-coordinate IrIII complex, coordinated by a bidentate diazomethylenephosphorane, a benzaldimine, a chelating dppm moiety and an iodido ligand. The phosphorus atoms of the chelating dppm are trans to the central carbon atom of the diazomethylenephosphorane and the iodide ligand, respectively. Both an iodide and a triiodide moiety function as counter-ions. The acetonitrile solvent molecules in 3 are severely disordered in position and occupation. In 4, the I3− anion is positionally disordered (ratio roughly 1:1), as is the I− anion with a ratio of 9:1. The dichloromethane solvent molecule lies near a twofold rotation axis (disorder) and was refined with an occupancy of 0.5. Another disorder occurs for the solvent methanol with a 1:1 ratio.

Keywords

• crystal structure
• carbodiphosphorane
• divalent carbon
• triazene
• fragmentation
• diazomethylenephosphorane
• diazophosphorane
• nitrene
• iridium(III)