Crystal structures of two PCN pincer iridium complexes and one PCP pincer carbodiphosphorane iridium intermediate: substitution of one phosphine moiety of a carbodiphosphorane by an organic azide

Abstract

The structure of [Ir{(4-Cl-C6H4N3)C(dppm)-κ3P,C,N}(dppm-κ2P,P′)]Cl·1.5CH2Cl2·0.5C7H8 (C57H48Cl2IrN3P4·1.5CH2Cl2·0.5C7H8) (2), dppm = bis(diphenylphosphino)methane {systematic name: [7-(4-chlorophenyl)-1,1,3,3-tetraphenyl-5,6,7-triaza-κN7-1,3λ4-diphospha-κP1-hepta-4,6-dien-4-yl][methylenebis(diphenylphosphine)-κ2P,P′]iridium(I) chloride–dichloromethane–toluene (2/3/1)}, resulting from the reaction of [IrClH{C(dppm)2-κ3P,C,P)(MeCN)]Cl (1a) with 1-azido-4-chlorobenzene, shows a monocationic five-coordinate IrI complex with a distorted trigonal–bipyramidal geometry. In 2, the iridium centre is coordinated by the neutral triazeneylidenephosphorane (4-Cl-C6H4N3)C(dppm) acting as a PCN pincer ligand, and a chelating dppm unit. The structure of the coordination compound [IrCl(CN)H(C(dppm)2-κ3P,C,P)]·CH3CN, (C52H45ClIrNP4·CH3CN) (1b) [systematic name: chloridocyanidohydrido(1,1,3,3,5,5,7,7-octaphenyl-1,3λ5,5λ4,7-tetraphospha-κ2P1,P7-hept-3-en-4-yl)iridium(III) acetonitrile monosolvate], prepared from 1a and KCN, reveals an octahedral IrIII central atom with a meridional PCP pincer carbodiphosphorane (CDP) ligand; the chloride ligand is located trans to the central carbon of the CDP functionality while the hydrido and cyanido ligands are situated trans to each other. The chiral coordination compound [Ir(CN)((4-Cl-C6H4N3)CH(CH(P(Ph)2)2)-κ3P,C,N)(dppm-κ2P,P′)]·2CH3OH, (C58H48ClIrN4P4·2CH3OH) (3) (systematic name: {4-[3-(4-chlorophenyl)triazenido-κN3]-1,1,3,3-tetraphenyl-1,3λ5-diphospha-κP1-but-2-en-4-yl}cyanido[methylenebis(diphenylphosphine)-κ2P,P′]iridium(III) methanol disolvate), formed via prolonged reaction of 1-azido-4-chlorobenzene with 1b, features a six-coordinate IrIII central atom. The iridium centre is coordinated by the dianionic facial PCN pincer ligand [(4-Cl-C6H4N3)CH(CH(P(Ph2)2)2)], a cyanido ligand trans to the central carbon of the PCN pincer ligand and a chelating dppm unit. Complex 2 exhibits a 2:1 positional disorder of the Cl− anion. The CH2Cl2 and C7H8 solvent molecules show occupational disorder, with the toluene molecule exhibiting additional 1:1 positional disorder with some nearly overlying carbon atoms.

Keywords

• crystal structure
• carbodiphosphorane
• iridium
• organic azide
• reductive elimination
• PCP pincer
• non-innocent behaviour
• PCN pincer