PROCESS FOR POLYMERIZATION OF ETHYLENE, PYRIDINEBISIMINES AND PYRIDINEBISIMINES COMPLEXES WITH IRON AND COBALT

1. A process for the polymerization of ethylene, comprising, contacting, at a temperature of about -100 degree C to about +200 degree C, a compound of the formula: with ethylene and: (a) a first compound W, which is a neutral Lewis acid capable of abstracting X from M to from WX, and which is also capable of transferring an alkyl group or a hydride to M, provided that WX is a weakly coordinating anion; or (b) a combination of a second compound which is capable of transferring an alkyl or hydride group to M and a third compound which is a neutral Lewis acid which is capable of abstracting X, from M to form a weakly coordinating anion; wherein: M is Co or Fe; each X is an anion; n is 1, 2 or 3 so that the total number of negative charges on said anion or anions is equal to the oxidation sate of a Fe or Co atom present in (II): R , R and R are each independently hydrogen, CF3; R and R are each independently hydrogen, halogen, C1-6alkyl, C1-6alkylthio, 1-imidazolyl; R and R are optionally substituted phenyl. 2. The process according to claim 1 in which said compound is or becomes a part of heterogenic catalyst on a solid carrier. 3. The process according to claim 1 which is carried out in gas or liquid phases. 4. The process according to claim 1 wherein said neutral Lewis acid is an alkyl aluminum compound. 5. The process according to claim 1 wherein a pressure of said ethylene is about atmospheric pressure to about 275 MPa. 6. The process according to claim 1 wherein polyethylene with an average DP of 40 or more is produced. 7. The process for or the polymerization of ethylene, comprising contacting, at a temperature of about -100 degree C to about +200 degree C, a Co[II], Co[III], Fe[II] or Fe[III] complex of a tridentate ligand of the formula with ethylene, wherein: R , R and R are each independently hydrogen, CF3; R and R are each independently hydrogen, halogen, C1-6alkyl, C1-6alkylthio, 1-imidazolyl; R and R are optionally substituted phenyl; and provided that a Co[II], Co[III], Fe[II] or Fe[III] atom also has bonded to it an empty coordination site or a ligand that may be displaced by said ethylene, and a ligand that may add to said ethylene. 8. The process according to claim 1 in which said compound is or becomes a part of heterogenic catalyst on a solid carrier. 9. The process according to claim 7 which is carried out in gas or liquid phases. 10. The process according to claim 7 wherein a pressure of said ethylene is about atmospheric pres