Crystal structures of the IrIII{C(C4H6O2)(dppm)-κ3PCO}(dppm)H(CF3O3S)2 and IrIII{C(C4H6O2)(dppm)-κ2PC}(CO)(dppm)H(CF3O3S)2 phosphorus ylide complexes generated by a Wittig-type carbon–carbon coupling reaction of a carbodiphospho­rane PCP ligand system

摘要

The reaction of [Ir^III{C(dppm)2-κ³ P,C,P′}ClH(NH3C2)]Cl with ethyl diazo­acetate, a well known C=C coupling reagent, leads to the formation of a C=C unit, accompanied by N2 abstraction, reorganization of a dppm subunit and, considered as a whole, to the transformation of the PCP pincer carbodi­phospho­rane system to a phospho­rus ylide ligand. After removal of the halogenides, the iridium center is stabilized by the carbonyl O atom through the formation of a five-membered chelate ring. A PCO pincer ligand system is thereby generated, which coordinates the iridium(III) atom threefold in a facial manner. The phospho­rus electron-donor atoms and the ylide carbon atom of the resulting [Ir^III{C(C4H6O2)(dppm)-κ³ P,C,O}(dppm)H](CF3O3S)2 complex, also termed as [bis­(di­phenyl­phosphan­yl)methane]({[(di­phenyl­phosphan­yl)meth­yl]di­phenyl­phosphanyl­idene}(eth­oxy­oxoethanyl­idene)methanyl­idene-κ³ P,C,O)hydridoiridium(III) bis­(tri­fluoro­methane­sulfonate), are in plane and the hydrido ligand and the carbonyl O atom are located trans to each other, perpendicular to the meridional plane. The addition of carbon monoxide causes a replacement of the carbonyl O atom of the acetate subunit by a carbonyl ligand, thereby creating [bis­(di­phenyl­phosphan­yl)methane]­carbon­yl({[(di­phenyl­phosphan­yl)meth­yl]di­phenyl­phosphanyl­idene}(eth­oxy­oxoethanyl­idene)methanyl­idene-κ² P,C}hydridoiridium(III) bis­(tri­fluoro­methane­sulfonate)–di­chloro­methane–ethyl acetate (6/2/3) or, more simply, [Ir^III{C(C4H6O2)(dppm)-κ² P,C}(CO)(dppm)H](CF3O3S)2·0.33CH₂Cl₂·0.5C₄H₈O₂. One tri­fluoro­meth­ane­sulfonate counter-ion of >3 shows positional disorder in a 2:1 ratio. Complex >4 shows pseudo-merohedral twinning (matrix: 0 0 0 0 1 0 1). The di­chloro­methane solvent is disordered over two orientations with occupation factors of 0.5 and 0.166.