Crystal structures of the [Ir III {C(C 4 H 6 O 2 )(dppm)-κ 3 P , C , O }(dppm)H](CF 3 O 3 S) 2 and [Ir III {C(C 4 H 6 O 2 )(dppm)-κ 2 P , C }(CO)(dppm)H](CF 3 O 3 S) 2 phosphorus ylide complexes, generated by a Wittig-type carbon–carbon coupling reaction of a carbodiphosphorane PCP ligand system

• Published in: Acta crystallographica. Section E, Crystallographic communications Crystallographic communications, 2018-11, Vol.74 (11), p.1643-1647
• Main Authors: Schlapp-Hackl, Inge, Pauer, Bettina, Falschlunger, Christoph, Schuh, Walter, Kopacka, Holger, Wurst, Klaus, Peringer, Paul
• Format: Article
• Language: English
• Subjects: C=C coupling reaction; carbodiphosphorane (CDP); crystal structure; ethyl diazoacetate; iridium(III); NMR; PCP pincer
• ISSN: 2056-9890; 2056-9890
• DOI: 10.1107/S205698901801455X

The reaction of [Ir III {C(dppm) 2 -κ 3 P , C , P ′}ClH(NH 3 C 2 )]Cl with ethyl diazoacetate, a well known C=C coupling reagent, leads to the formation of a C=C unit, accompanied by N 2 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(C 4 H 6 O 2 )(dppm)-κ 3 P , C , O }(dppm)H](CF 3 O 3 S) 2 complex, also termed as [bis(diphenylphosphanyl)methane]({[(diphenylphosphanyl)methyl]diphenylphosphanylidene}(ethoxyoxoethanylidene)methanylidene-κ 3 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-κ 2 P , C }hydridoiridium(III) bis(trifluoromethanesulfonate)–dichloromethane–ethyl acetate (6/2/3) or, more simply, [Ir III {C(C 4 H 6 O 2 )(dppm)-κ 2 P , C }(CO)(dppm)H](CF 3 O 3 S) 2 ·0.33CH 2 Cl 2 ·0.5C 4 H 8 O 2 . One trifluoromethanesulfonate counter-ion of 3 shows positional disorder in a 2:1 ratio. Complex 4 shows pseudo-merohedral twinning (matrix: \overline{1} 0 0 0 \overline{1} 0 1 0 1). The dichloromethane solvent is disordered over two orientations with occupation factors of 0.5 and 0.166.