Cationic Iridium(I) NHC-Phosphinidene Complexes and Their Application in Hydrogen Isotope Exchange Reactions

The reaction of the dimeric iridium complex [Ir(cod)Cl](2) (cod=1,5-cyclooctadiene) with the N-heterocyclic carbene-phosphinidene adduct (IDipp)PH (1, IDipp=1,3-bis(2,6-diisopropylphenyl)imidazolin-2-ylidene) afforded the neutral bimetallic iridium(I) complex [mu-{(IDipp)PH}{Ir(cod)Cl}(2)] (2), and further addition of IDipp(PH) (1) yielded the corresponding monometallic iridium(I) complex [{(IDipp)PH}Ir(cod)Cl] (3). Dechlorination of these complexes with sodium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate (NaBAr4F) yielded their cationic derivatives [{mu-(IDipp)PH}{Ir(cod)}(2){mu-Cl}][BAr4F] (4) and [{(IDipp)PH}Ir(cod)(PPh3)][BAr4F] (5). All complexes were structurally characterized and showed the expected square-planar coordination geometry and significant polarization of the P-C bond of the NHC-phosphinidene adduct upon metal coordination. The complexes 4 and 5 were tested for their applicability in catalytic H/D exchange reactions, and both complexes showed high activity for a broad range of aromatic substrates, ranging from ketones, amides, esters, nitro compounds and heterocycles.

Automated summary

This study reports the synthesis of novel iridium complexes and their application in catalytic reactions. Neutral and cationic complexes were obtained through reactions with specific ligands, and these complexes exhibited high activity in catalytic reactions of aromatic substrates.