  In this manuscript we present a computational study on the photoluminescence
properties of several heteroleptic [Ru(H)(CO)(N^N)(tpp)2]+ complexes (tpp =
triphenylphosphine). A special focus is set on disentangling the
temperature-dependent emissive properties. Experimentally, when cooling a
solution of [Ru(H)(CO)(dmphen)(tpp)2]+ (dmphen =
5,6-dimethyl-1,10-phenanthroline) from room to cryogenic temperature, a partial
emission switch from metal-to-ligand charge transfer (3MLCT) to ligand-centered
(3LC) phosphorescence is observed, resulting in dual photoluminescence. Two
different origins of the anomalous emissions are possible, i.e., thermal
equilibration between electronically excited states or different excited state
solvent relaxation effects. Our calculations are in favor of the thermally
equilibrated scenario. This computational investigation highlights the
importance of controlling the temperature-dependent emissive behavior for
optoelectronic applications.
