Palladium(ii) N-heterocyclic allenylidene complexes with extended intercationic Pd⋯Pd interactions and MMLCT phosphorescence

Abstract

Extended intercationic Pd⋯Pd contacts of 3.30 Å in the crystal structure and distinct MMLCT transitions absorbing at 528 nm and emitting beyond 600 nm in solutions have been revealed with cyclometalated Pd(II) N-heterocyclic allenylidene complexes. The Pd(II)-based MMLCT excited states are responsive to concentrations, temperatures, mechanical force and organic vapors.