A compound according to Formula I, as well as, devices and formulations containing the compound as described. The compound has the general formula wherein n=1 or 2; wherein X1—X2 is a bidentate ligand having the formula: wherein each of R1, R2, R3, R4 and R5 is independently selected from the group consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof; wherein each of R3, R4 and R5 can also be selected from two adjacent substituents joined to form into a ring; wherein each of Z1, Z2, Z3, Z4, Z6, Z7, Z8 is independently selected from C, CH or N; wherein ring A is connected to ring B through N—C bond; and wherein Y1—Y2 is a different bidentate ligand other than X1—X2.