A process for preparing a compound having the formula L2IrL′ is provided. The process comprises: combining and L′ in the presence of an organic solvent to form a mixture, wherein L is a suitable carbene ligand precursor coordinated to Ir; and L′ is a bidentate ligand or two monodentate ligands, and L is different from L′; Also provided is a process for preparing a compound having the formula The process comprises: (a) combining L, a carbene ligand precursor, with an organic solvent; (b) maintaining the mixture of step (a) at a temperature from about 175° C. to less than the boiling point of the organic solvent in (a). A process for preparing a compound with the formula L3Ir is also provided. This process comprises combining and L in the presence of alcohol and a base to form a mixture, wherein L is a bidentate ligand that may form a five-membered chelate ring.