Iridium complexes of an ortho -trifluoromethylphenyl substituted PONOP pincer ligand.

The synthesis and iridium coordination chemistry of a new pyridine-based phosphinito pincer ligand 2,6-(Ar F 2 PO) 2 C 5 H 3 N (PONOP-Ar F ; Ar F = 2-(CF 3 )C 6 H 4 ) are described, where the P-donors have ortho -trifluoromethylphenyl substituents. The iridium(III) 2,2'-biphenyl (biph) derivative [Ir(PONOP-Ar F )(biph)Cl] was obtained by reaction with [Ir(biph)(COD)Cl] 2 (COD = 1,5-cyclooctadiene) and subsequent halide ion abstraction enabled isolation of [Ir(PONOP-Ar F )(biph)] + which features an Ir ← F-C bonding interaction in the solid state. Hydrogenolysis of the biphenyl ligand and formation of [Ir(PONOP-Ar F )(H) 2 ] + was achieved by prolonged reaction of [Ir(PONOP-Ar F )(biph)] + with dihydrogen. This transformation paved the way for isolation and crystallographic characterisation of low valent iridium derivatives through treatment of the dihydride with tert -butylethylene (TBE). The iridium(I) π-complex [Ir(PONOP-Ar F )(TBE)] + is thermally stable but substitution of TBE can be achieved by reaction with carbon monoxide. The solid-state structure of the mono-carbonyl product [Ir(PONOP-Ar F )(CO)] + is notable for an intermolecular anagostic interaction between the metal centre and a pentane molecule which co-crystallises within a cleft defined by two aryl phosphine substituents.