Nature of the emitting 3MLCT manifold of rhenium(I) (diimine) (CO) 3Cl complexes

Abstract

Spectroscopic investigations of four Re(NN) (CO) 3Cl complexes (NN = 2,2′-bipyridine, 4,4′-dimethyl-2,2′-bipyridine, 1,10-phenanthroline,or 2,9-dimethyl-1,10-phenanthroline) in the 77—4 K range reveal a single 3MLCT emitting configuration. Temperature dependences of the phosphorescence lifetimes have been analyzed in terms of a multiple state model that yields rate constants and level splittings. A model based on C 2v symmetry that depends on second-order spin-orbit coupling between dπ* configurations is proposed to rationalize the results. Implications for the well-studied Ru(NN) 2+ 3 and Os(II) (NN) 2+ 3 manifolds are discussed.