C–H Bond Cleavage of Acetonitrile by Iridium Complexes Bearing PNP-Pincer-Type Phosphaalkene Ligands

A novel parent amido complex of iridium­(I), K­[Ir­(NH2)­(PPEP*)] (3), coordinated with a dearomatized PNP-pincer-type phosphaalkene ligand (PPEP*) has been prepared by deprotonation with KHMDS from [Ir­(NH2)­(PPEP)] (2) having benzophospholanylmethyl and phosphaethenyl groups at the 2,6-positions of pyridine. Complex 3 has two base points at PPEP* and NH2 ligands and, thus, successively reacts with two molecules of CH3CN via heterolytic cleavage of the C–H bond. X-ray structural analysis of the product complex K­[Ir­(CH2CN)2(PPEP)] (5) reveals remarkable elongation of the PC bond indicative of the occurrence of strong π-back-donation from iridium to PPEP.