A compound comprising a first bidentate ligand LA, wherein LA comprises a structure of Formula I;






wherein Z is selected from the group consisting of O, S, NR, BR, CRKRL, SiRKRL, —CRKRLCRMRN—, —SiRKRLSiRMRN—, —CRKRLO—, —SiRKRLO—, and —CRK═CRL—;
wherein ring A, ring B, and ring C are each independently a 5-membered carbocyclic ring, 5-membered heterocyclic ring, 6-membered carbocyclic ring or 6-membered heterocyclic ring;
wherein LA is coordinated to a metal M forming a 5-membered chelate ring;
wherein M is selected from the group consisting of Ir, Pt, Pd, Ru, Rh, Os, Re, Cu, Ag, and Au;
wherein RA, RB, and RC each represent mono to the maximum allowable substitution, or no substitution;
wherein each R, RK, RL, RM, RN, RA, RB, and RC is independently a hydrogen or a substituent selected from the group consisting of deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, boryl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carboxylic acid, ether, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof;
wherein M is optionally coordinated to one or more other ligands;
wherein any two substituents are optionally joined or fused together to form a ring; and
with the provision that LA does not comprise the following structure: