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

Abstract

Compound [Ir(C8H12)(C51H45P4)](Cl)2 or [Ir(cod)(CH(dppm)2-3P,C,P)](Cl)2 (1a), was obtained from [IrCl(cod)]2 and the carbodiphosphorane (CDP) salt [CH(dppm)2]Cl [where cod = cycloocta-1,5-diene and dppm = bis(diphenylphosphino) methane]. Treatment of 1a with thallium(I) trifluoromethanesulfonate [Tl(OTf)] and subsequent crystallization gave complex [Ir(C8H12)(C51H45P4)](OTf)2-CH3CO2C2H5-CH2Cl2 or [Ir(cod)(CH(dppm)2-3P,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. Compound 1b represents the first example of a non-meridional coordination of the PCP pincer ligand [CH(dppm)2]+ with a P-Ir-P angle of 98.08 (2)-. Compound 2, [Ir(Cl)2(H)(C51H44P4)]-(CH3)2CO or [Ir(Cl)2(H)(C(dppm)2-3P,C,P)]-(CH3)2CO [systematic name: Dichloridohydrido( 1,1,3,3,5,5,7,7-octaphenyl-1,5-5,7-triphospha-3-phosphoniahept-4-en-4-yl)iridium(III) acetone monosolvate], crystallizes as an acetone monosolvate. It is a six-coordinate IrIII coordination compound. Here, the PCP pincer ligand is coordinated in a meridional manner; one chlorido ligand is positioned trans to the carbon donor, the remaining two coordination sites being occupied by the second chlorido and a hydrido ligand trans to each other. Complex 3, [Ir(Cl)2(H)(C51H45P4)]Cl-5H2O or [Ir(Cl)2(H)(CH(dppm)2-3P,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 of 2. The ligand [CH(dppm)2]+ is coordinated in a meridional manner. In the cationic six-coordinate IrIII complex 4, [Ir(Cl)(H)-(CO)(C51H44P4)]Cl-2CH3OH-H2O or [Ir(Cl)(H)(CO)(C(dppm)2-3P,C,P)]Cl-2CH3OH-H2O [systematic name: Carbonylchloridohydrido(1,1,3,3,5,5,7,7-octaphenyl-1,5-5,7-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 the meridional PCP ligand; the H and CO ligands are positioned axially to this plane and trans to each other.