Compound of formula 4 or formula 5 ##STR00001##
wherein
L is a neutral ligand, preferably a nitrogen-containing heterocyclic carbene (NHC) such as carbene containing at least two nitrogen atoms, a cyclic aminoalkyl carbene (CAAC) or a bicyclic aminoalkyl carbene (BICAAC);
R.sup.1, R.sup.3, R.sup.4, R.sup.5, R.sup.6, R.sup.7, R.sup.8, R.sup.9, R.sup.10 and R.sup.11 are, independently, H, unbranched or branched C.sub.1-20 alkyl, C.sub.5-9 cycloalkyl, unbranched or branched C.sub.1-20 alkoxy, optionally bearing one or more halogen atoms, respectively; or aryl, optionally substituted with one or more of unbranched or branched C.sub.1-20 alkyl, C.sub.5-9 cycloalkyl, unbranched or branched C.sub.1-20 alkoxy, aryl, aryloxy, unbranched or branched C.sub.1-20 alkylcarbonyl, arylcarbonyl, unbranched or branched C.sub.1-20 alkoxycarbonyl, aryloxycarbonyl, heteroaryl, carboxyl, cyano, nitro, amido, aminosulfonyl, N-heteroarylsulfonyl, unbranched or branched C.sub.1-20 alkylsulfonyl, arylsulfonyl, unbranched or branched C.sub.1-20 alkylsulfinyl, arylsulfinyl, unbranched or branched C.sub.1-20 alkylthio, arylthio, sulfonamide, halogen or N(R.sup.y)(R.sup.z), wherein R.sup.y and R.sup.z are independently selected from H and C.sub.1-20 alkyl:
R.sup.2 is H, unbranched or branched C.sub.1-20 alkyl.

The invention relates to oligomerization of olefins, such as ethylene, to higher olefins, such as a mixture of 1-hexene and 1-octene, using a catalyst system that comprises a) a source of chromium b) one or more activators and c) a phosphacycle-containing ligating compound. Additionally, the invention relates to a phosphacycle-containing ligating compound and a process for making said compound.

The invention relates to oligomerization of olefins, such as ethylene, to higher olefins, such as a mixture of 1-hexene and 1-octene, using a catalyst system that comprises a) a source of chromium b) one or more activators and c) a phosphacycle-containing ligating compound. Additionally, the invention relates to a phosphacycle-containing ligating compound and a process for making said compound.

The invention relates to oligomerization of olefins, such as ethylene, to higher olefins, such as a mixture of 1-hexene and 1-octene, using a catalyst system that comprises a) a source of chromium b) one or more activators and c) a phosphacycle-containing ligating compound. Additionally, the invention relates to a phosphacycle-containing ligating compound and a process for making said compound.

The invention relates to oligomerization of olefins, such as ethylene, to higher olefins, such as a mixture of 1-hexene and 1-octene, using a catalyst system that comprises a) a source of chromium b) one or more activators and c) a phosphacycle-containing ligating compound. Additionally, the invention relates to a phosphacycle-containing ligating compound and a process for making said compound.

The invention relates to oligomerization of olefins, such as ethylene, to higher olefins, such as a mixture of 1-hexene and 1-octene, using a catalyst system that comprises a) a source of chromium b) one or more activators and c) a phosphacycle-containing ligating compound. Additionally, the invention relates to a phosphacycle-containing ligating compound and a process for making said compound.

The invention relates to oligomerization of olefins, such as ethylene, to higher olefins, such as a mixture of 1-hexene and 1-octene, using a catalyst system that comprises a) a source of chromium b) one or more activators and c) a phosphacycle-containing ligating compound. Additionally, the invention relates to a phosphacycle-containing ligating compound and a process for making said compound.

The invention relates to oligomerization of olefins, such as ethylene, to higher olefins, such as a mixture of 1-hexene and 1-octene, using a catalyst system that comprises a) a source of chromium b) one or more activators and c) a phosphacycle-containing ligating compound. Additionally, the invention relates to a phosphacycle-containing ligating compound and a process for making said compound.

The invention relates to oligomerization of olefins, such as ethylene, to higher olefins, such as a mixture of 1-hexene and 1-octene, using a catalyst system that comprises a) a source of chromium b) one or more activators and c) a phosphacycle-containing ligating compound. Additionally, the invention relates to a phosphacycle-containing ligating compound and a process for making said compound.

The invention relates to oligomerization of olefins, such as ethylene, to higher olefins, such as a mixture of 1-hexene and 1-octene, using a catalyst system that comprises a) a source of chromium b) one or more activators and c) a phosphacycle-containing ligating compound. Additionally, the invention relates to a phosphacycle-containing ligating compound and a process for making said compound.