"Such metals include, in particular, the heavy metals having an atomic number of at least 72, such as Os, Ir, Pt and Au, with Ir and Pt being particularly preferred metals. [0051] In addition to being bound to at least one mono-anionic, bidentate, carbon-coordination ligand, the metal atom of the organometallic compounds of the present invention is also bound to at least one non-mono-anionic, biden" . . . .