Patent ID: 7019158

Claim:
A compound of formula (1): wherein: L is optionally one or more groups which are removable during a chemical reaction; M is a transition metal selected from Groups 6, 7, 8, 9 and 10; Y is an optionally substituted linking group; A is an optionally substituted heteroatom capable of bonding or coordinating to metal (M); and EITHER: (a) R 5 and R 6 are hydrogen: R 1 is optionally substituted hydrocarbyl, optionally substituted heterocyclyl, or tri-hydrocarbylsilyl, or R 1 & Y are linked in such a way as to form an asymmetrically substituted ring, or R 1 & A are linked in such a way as to form an optionally substituted heterocyclic ring; R 2 is optionally substituted hydrocarbyl, optionally substituted heterocyclyl, or tri-hydrocarbylsilyl; R 3 and R 4 are independently optionally substituted hydrocarbyl, optionally substituted heterocyclyl, tri-hydrocarbylsilyl or hydrogen; or one or more of R 2 & R 3 and R 3 & R 4 are linked in such a way as to form an optionally substituted ring optionally comprising one or more heteroatoms; provided that R 2 , R 3 and R 4 are selected such that the cyclopentadiene ring to which they are attached is asymmetrically substituted; OR; (b) R 3 is hydrogen, optionally substituted hydrocarbyl, optionally substituted heterocyclyl, or tri-hydrocarbylsilyl; and either (i) R 5 & R 2 are linked in such a way as to form an optionally substituted non-aromatic ring system optionally comprising one or more heteroatoms; and R 1 , R 4 and R 6 are independently hydrogen, optionally substituted hydrocarbyl, optionally substituted heterocyclyl, or tri-hydrocarbylsilyl; or R 1 & R 6 are linked in such a way as to form an optionally substituted non-aromatic ring system optionally comprising one or more heteroatoms and R 4 is hydrogen, optionally substituted hydrocarbyl, optionally substituted heterocyclyl, or tri-hydrocarbylsilyl; or R 4 & R 6 are linked in such a way as to form an optionally substituted ring optionally comprising one or more heteroatoms and R 1 is hydrogen, optionally substituted hydrocarbyl, optionally substituted heterocyclyl, or tri-hydrocarbylsilyl; or (ii) R 5 , R 1 & R 2 are linked in such a way as to form an optionally substituted non-aromatic asymmetric ring system optionally comprising one or more heteroatoms; and R 4 and R 6 are idependently hydrogen, optionally substituted hydrocarbyl, optionally substituted heterocyclyl, or tri-hydrocarbylsilyl; or R 4 & R 6 are linked in such a way as to form an optionally substituted ring optionally comprising one or more heteroatoms.