Ligand effect of cyclometallated iridium(iii) complexes on N-alkylation of amines in hydrogen borrowing reactions

Abstract

Dinuclear iridium complexes with the general formula (C^N)₂Ir(μ-Cl)₂Ir(C^N)₂ (C^N = bidentate ligand with carbon and nitrogen donor atoms) were prepared and used in catalytic systems for N-alkylation of amines through the hydrogen borrowing pathway. Triphenylphosphine derivatives were used as auxiliary in catalytic systems to provide excellent conversion of amines to N-alkylation products in yields ranging from 57% to 100%. The catalytic ability of the catalyst depends on the structure of its coordination ligands, including bidentate ligands (C^N) and triphenylphosphine derivatives. These catalytic systems adopt an environmentally friendly and sustainable reaction process through a hydrogen self-transfer strategy, using readily available alcohols as alkylating agents without the need for bases, solvents, and other additives, showing potential in the synthetic and pharmaceutical industries.