A New Class of Luminescent Polypyridine Complexes of Rhenium(I) Containing cis-Carbonyl Ligands

A new class of long-lived luminescent complexes of the type cis-ReI(CO)2(N-N)(P-P)+ (where N-N is a chelate polypyridine ligand and P-P is a chelate phosphine) has been prepared. The new Re excited states are of extraordinary stability and exhibit red-shifted spectral responses relative to the well-studied fac-Re(bpy)(CO)3L(+/0) series (L is a variety of neutral and anionic ligands). Of primary interest are their extremely long lifetimes in CH2Cl2 solution, which could be a consequence of an energy gap law different from that of the tricarbonyl complexes.