Chromium complex and catalyst therefrom

A catalyst system comprising a) a source of chromium;

• b) one or more activators;
• and, c) at least one phosphacycle-containing ligating compound of the formula (I):
• wherein:
• P is phosphorus:
• L is C;
• q is 1 or 2:
• p is 2, wherein a first of L1 is N and q is 0 or 1 to give
• and a second of L1 is Si and q is 1 or 2 to give
• R5 attached to L1 is independently H, C1-40 substituted or unsubstituted alkyl, C1-40 substituted or unsubstituted aryl;
• each of R3 and R4 independently is ethyl, substituted or unsubstituted phenyl, unsubstituted furanyl, unsubstituted thienyl, or form a ring group to give compound of formula (II):
• wherein the substituent on the substituted phenyl is selected from halogen, C1-4 alkyl, C1-4 alkoxy, or C6-10 aryl;
• each R5 attached to the C or L group is independently H, halogen, C1-40 substituted or unsubstituted alkyl, C1-40 substituted or unsubstituted aryl;
• two or more R5 groups linked to separate L atoms in a phosphacycle moiety are optionally linked together to form a cyclic structure that contains from 3 to 10 ring atoms;
• and
• two R5 groups attached to the same L atom may be optionally linked together to form a cyclic structure that contains from 3 to 10 ring atoms.