Metalated Ir–CNP Complexes Containing Imidazolin‐2‐ylidene and Imidazolidin‐2‐ylidene Donors – Synthesis, Structure, Luminescence, and Metal–Ligand Cooperative Reactivity

The iridium complex 1 based on a metalated CNP ligand containing an imidazolin‐2‐ylidene fragment has been prepared by treatment of the ligand precursor 4 with Ag 2 O followed by reaction with [IrCl(COE) 2 ] 2 . The chlorohydride imidazolidin‐2‐ylidene complex 6 , which is isostructural to 1 , was synthetized by reaction of the previously reported dihydride derivative 3 with CH 2 Cl 2 . Complexes 1 and 6 exhibit luminescence arising from a 3 MLCT/ILCT state involving the metalated CNP ligand, which is particularly intense for 1 in the solid state at 298 K. Furthermore, the reactivity of complexes 1 and 6 towards bases was compared. Deprotonation of 1 with KO t Bu produced the selective formation of the dinuclear complex 7 ; meanwhile, the reaction of 6 led to a complex mixture of products. The same reactions carried out in the presence of PPh 3 produced the selective deprotonation of the P‐bonded methylene bridges of 1 and 6 , yielding the isostructural derivatives 9 and 10 . DFT calculations performed on the u NHC‐containing tautomers I and II , and the s NHC‐based isomers III and IV , showed that the NHC‐deprotonated derivatives II and IV are more stable by 3.20 and 2.73 kcal mol –1 , respectively, than their P‐deprotonated counterparts ( I and III ). However, a reverse stability order was observed for hexacoordinated tautomers I·L and II·L , and III·L and IV·L (L = PPh 3 , CO, MeCN). Finally, the catalytic activity of complex 3 in the transfer hydrogenation of ketones has been assessed.