摘要 |
The present invention provides the use of certain complexes of a group 3 to 10 transition metal or a lanthanide (M) and a ligand of formula (I), wherein each group A, which may be the same or different, is an M-coordinating carbon or heteroatom or eta <q> group, at least one group A being an M-coordinating carbene carbon, silicon, germanium or phosphorus (i.e. C:, Si:, Ge: or P:) which is a ring member of a 4- or 5- ring atom heterocycle; each L, which may be the same or different, is a bond or bridging group providing a 1 to 5 atom chain between the groups it connects; R is a hydrogen atom or a C1-20 hydrocarbyl group optionally attached by a silicon atom or a Si-O- group; each R*, which may be the same or different, is a group R or together both R* are a bond whereby to form an 8 to 22 ring atom macrocycle; n is 0 or 1; m is 0 or 1; p is 0, 1 or 2; and q is an integer having a value of 2 to 6; as catalysts, procatalysts, or catalyst precursors. |