A compound comprising a first ligand LA of Formula I or Formula II: wherein A1 and A2 are each independently C or Si; wherein each RA, and RB independently represents mono to the maximum allowable substitution, or no substitution; wherein each X1, X2, and X3 is independently C or N; wherein each R, R1, R2, R3, R4 and RA 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 LA is complexed to a metal M; wherein M is optionally coordinated to one or more other ligands; wherein the ligand LA is optionally linked with the one or more other ligands to form a tridentate, tetradentate, pentadentate, or hexadentate ligand; and wherein any two substituents are optionally joined or fused together to form a ring.