A luminescent organometallic complex composition of matter, a method of preparing this composition of matter, and an electronic device built with this composition of matter. The composition includes: at least one transition metal that produces phosphorescent emission at room temperature, at least one first monoanionic bidentate ligand coordinated through a nitrogen on a heteroaromatic ring and a carbon, and at least one second ligand selected from a hydride and a ligand coordinated through a carbon atom which is part of an aromatic group.