Crystal structure of an iridium(III) complex of the [C(dppm)] PCP pincer ligand system and its conjugate CH acid form.

After the successful creation of the newly designed PCP carbodi-phospho-rane (CDP) ligand [Reitsamer (2012 ▸). , 3503-3514; Stallinger (2007 ▸). pp. 510-512], the treatment of this PCP pincer system with the transition metal iridium and further the analysis of the structures by single-crystal diffraction and by NMR spectroscopy were of major inter-est. Two different iridium complexes, namely (bis-{[(di-phenyl-phosphan-yl)meth-yl]di-phenyl-phosphanyl-idene}methane-κ,,')carbonyl-chlorido-hydridoiridium(III) chloride di-chloro-methane tris-olvate, [Ir(CO){C(dppm)-κ,,'}ClH]Cl·3CHCl () and the closely related (bis-{[(di-phenyl-phosphan-yl)meth-yl]di-phenyl-phosphanyl-idene}methanide(1+)-κ,,')carbonyl-chlorido-hy-dridoirid-ium(III) dichloride-hydro-chloric acid-water (1/2/5.5), [Ir(CO){CH(dppm)-κ,,')ClH]Cl} (), have been designed and both complexes show a slightly distorted octa-hedral coordinated Ir centre. The PCP pincer ligand system is arranged in a manner, the CO ligand is located to the central PCP carbon and a hydride and chloride are located perpendicular above and below the PC plane. With an Ir-C distance of 2.157 (5) Å, an Ir-CO distance of 1.891 (6) Å and a quite short C-O distance of 1.117 (7) Å, complex presents a strong carbonyl bond. Complex , the corresponding CH acid of , shows an additionally attached proton at the carbodi-phospho-rane carbon atom located to the hydride of the metal centre. In comparison with complex , the Ir-C distance of 2.207 (3) Å is lengthened and the Ir-C-O values indicate a weaker influence of the central carbodi-phospho-rane carbon atom.