Patent ID: 7250510

Claim:
A compound of the formula I: wherein R 1 and R 2 are independently or simultaneously selected from the group consisting of C 1-20 alkyl, C 3-20 cycloalkyl, aryl and heteroaryl, said latter 4 groups being optionally substituted and/or one or more of the CH 2 groups in C 1-20 alkyl and/or C 3-20 cycloalkyl is optionally replaced with a heteroatom selected from the group consisting of O, S, and NR 5 ; R 3 and R 4 are independently or simultaneously selected from the group consisting of H, halo, C 1-20 alkyl, OC 1-20 alkyl, C 3-20 cycloalkyl, OC 3-20 cycloalkyl, aryl, O-aryl, heteroaryl and O-heteroaryl, said latter 8 groups being optionally substituted and/or one or more of the CH 2 groups in C 1-20 alkyl, OC 1-20 alkyl, C 3-20 cycloalkyl and/or OC 3-20 cycloalkyl is optionally replaced with a heteroatom selected from the group consisting of O, S, and NR 5 ; or R 3 and R 4 are linked to form an optionally substituted 4 to 12-membered ring system which optionally contains one or more heteroatoms selected from the group consisting of O, S, and NR 5 ; R 5 is selected from the group consisting of H and C 1-6 alkyl; is a single or a double bond; a is 1, 2 or 3; M is a transition metal; b is an integer representing the number of the anionic ligands X required to fulfill the valency requirements of M; X is an anionic ligand and when b is greater than 1, each X may be the same or different; L is a 5- to 6-membered optionally substituted N-containing aromatic heterocycle coordinated to M through N, which is optionally benzofused, and/or optionally contains one or more other heteroatoms selected from the group consisting of O, S, and NR 5 , and/or one or more of the optional substituents on the N-containing aromatic heterocycle is bonded to M in place of one or more X; or L is R 6 —CH═CH—R 7 in which R 6 and R 7 are independently or simultaneously selected from the group consisting of C 1-20 alkyl, OC 1-20 alkyl, C 3-20 cycloalkyl, OC 3-20 cycloalkyl, aryl, O-aryl, heteroaryl and O-heteroaryl, said latter 8 groups being optionally substituted; one or more of the carbons of the alkyl and cycloalkyl groups of R 6 and R 7 are optionally replaced with —C(O)—, —C(O)NR 5 — and —C(O)O—; aryl is an optionally substituted mono- or polycyclic aromatic radical containing from 6 to 14 carbon atoms; heteroaryl is a mono- or polycyclic heteroaromatic radical containing from 5 to 14 atoms, of which 1 to 5 atoms may be a heteroatom selected from the group consisting of S, O, N and NR 5 ; and optionally substituted means that one or more of the hydrogens on the group are optionally replaced with halo, OH, C 1-6 alkyl, OC 1-6 alkyl, fluoro-substituted C 1-6 alkyl, fluoro-substituted OC 1-6 alkyl, aryl or aryl that is substituted with 1-5 substituents independently or simultaneously selected from the group consisting of fluoro, C 1-4 alkyl, OC 1-4 alkyl, fluoro-substituted C 1-4 alkyl and fluoro-substituted OC 1-4 alkyl.