Patent ID: 8492749

Claim:
A compound of formula (I) wherein the ring A, represents an optionally substituted aryl group which can optionally contain heteroatoms, the ring B, represents an optionally substituted nitrogen containing aryl group, which can optionally contain further heteroatoms, or the ring A may be taken with the ring B binding to the ring A to form a ring; the group C, represents an acyclic carbene or a cyclic carbene (ring C), which can optionally contain heteroatoms, the ring D, represents an optionally substituted aryl group which can optionally contain heteroatoms, n1 is an integer of 1 to 3, m1 is an integer of 0, 1 or 2, m2 is an integer 0 or 1, M 1 is a metal with an atomic weight of greater than 40, L 3 is a monodentate ligand or a bidentate ligand, Y is —C(═O)— or —C(X 1 ) 2 —, wherein X 1 is hydrogen or C 1-4 alkyl and y is 0 or 1; with the proviso that the following compounds wherein L-L=η 4 −1,5-cyclooctadiene and Ar=2,6-diisopropylphenyl, are excluded.