Crystal structures of four new iridium complexes, each containing a highly flexible carbodiphosphorane PCP pincer ligand

Abstract

Compound [Ir(C8H12)(C51H45P4)]Cl2or [Ir(cod)(CH(dppm)2-κ3P,C,P)]Cl2(1a), was obtained from [IrCl(cod)]2and the carbodiphosphorane (CDP) salt [CH(dppm)2]Cl [where cod = cycloocta-1,5-diene and dppm = bis(diphenylphosphino)methane]. Treatment of1awith thallium(I) trifluoromethanesulfonate [Tl(OTf)] and subsequent crystallization gave complex [Ir(C8H12)(C51H45P4)](OTf)2·CH3CO2C2H5·CH2Cl2or [Ir(cod)(CH(dppm)2-κ3P,C,P)](OTf)2·CH3CO2C2H5·CH2Cl2(1b) [systematic name: (cycloocta-1,5-diene)(1,1,3,3,5,5,7,7-octaphenyl-1,7-diphospha-3,5-diphosphoniaheptan-4-yl)iridium(I) bis(trifluoromethanesulfonate)–ethyl acetate–dichloromethane (1/1/1)]. This five-coordinate iridium(I) complex cation adopts a trigonal–bipyramidal geometry with the CDP carbon and one cod double bond in axial sites. Compound1brepresents the first example of a non-meridionalcoordination of the PCP pincer ligand [CH(dppm)2]+with a P—Ir—P angle of 98.08 (2)°. Compound2, [IrCl2H(C51H44P4)]·(CH3)2CO or [IrCl2H(C(dppm)2-κ3P,C,P)]·(CH3)2CO [systematic name: dichloridohydrido(1,1,3,3,5,5,7,7-octaphenyl-1,5λ5,7-triphospha-3-phosphoniahept-4-en-4-yl)iridium(III) acetone monosolvate], crystallizes as an acetone monosolvate. It is a six-coordinate IrIIIcoordination compound. Here, the PCP pincer ligand is coordinated in ameridionalmanner; one chlorido ligand is positionedtransto the carbon donor, the remaining two coordination sites being occupied by the second chlorido and a hydrido ligandtransto each other. Complex3, [IrCl2H(C51H45P4)]Cl·5H2O or [IrCl2H(CH(dppm)2-κ3P,C,P)]Cl·5H2O [systematic name: dichloridohydrido(1,1,3,3,5,5,7,7-octaphenyl-1,7-diphospha-3,5-diphosphoniaheptan-4-yl)iridium(III) chloride pentahydrate], represents the conjugate CH acid of2. The ligand [CH(dppm)2]+is coordinated in ameridionalmanner. In the cationic six-coordinate IrIIIcomplex4, [IrClH(CO)(C51H44P4)]Cl·2CH3OH·H2O or [IrClH(CO)(C(dppm)2-κ3P,C,P)]Cl·2CH3OH·H2O [systematic name: carbonylchloridohydrido(1,1,3,3,5,5,7,7-octaphenyl-1,5λ5,7-triphospha-3-phosphoniahept-4-en-4-yl)iridium(III) chloride–methanol–water (1/2/1)], the chlorido ligand is found in the plane defined by the Ir center and themeridionalPCP ligand; the H and CO ligands are positioned axially to this plane andtransto each other.