Disclosed herein are novel light-emitting materials of Formula I and II below. These new complexes are synthesized and found to be sufficiently stable to allow sublimation and vacuum deposition. These new emitters are electrophosphorescent and can be used in organic light-emitting devices (OLEDs) for device elements capable of emitting light of color ranging from orange to red with high-efficiency and high-brightness. ##STR1## wherein E=Group 16 elements (including sulphur); M=Group 10 metal (including platinum); R₁-R₁₄ are each independently selected from the group consisting of hydrogen; halogen; alkyl; substituted alkyl; aryl; substituted aryl, with substituents selected from the group consisting of halogen, lower alkyl and recognized donor and acceptor groups. R₁ can also be selected from (CC)_nR₁₅, where (CC) represents a carbon-carbon triple bond (acetylide group), n is selected from 1 to 10, and R₁₅ is selected from alkyl, aryl, substituted aryl, and tri(alkyl)silyl.