US Patent 7300904 Trimerisation and oligomerisation of olefins using a chromium based catalyst

The invention provides a mixed heteroatomic ligand for an oligomerisation of olefins catalyst, which ligand includes at least three heteroatoms, of which at least one heteroatom is sulfur and at least 2 heteroatoms are not the same. The invention also provides a multidentate mixed heteroatomic ligand for an oligomerisation of olefins catalyst, which ligand includes at least three heteroatoms of which at least one is a sulfur atom. The ligand may also contain, in addition to sulfur, at least one nitrogen or phosphorous heteroatom.