Highly activated bimetallic complexes and polymerization process

A composition comprising:

• 1) one or more bimetallic complexes corresponding to the formula:
• wherein:
• M and M′ are independently Group 3, 4, 5, 6, or Lanthanide metals;
• L is a divalent group (or trivalent group if bound to Q) having up to 50 nonhydrogen atoms and containing an aromatic π-system through which the group is bound to M, said L also being bound to Z;
• L′ is a monovalent group or a divalent group (if bound to L″ or Q), or a trivalent group (if bound to both L″ and Q) having up to 50 nonhydrogen atoms and containing an aromatic π-system through which the group is bound to M′;
• L″ is a monovalent group or a divalent group (if bound to L′ or Q), or a trivalent group (if bound to both L′ and Q) having up to 50 nonhydrogen atoms and containing an aromatic π-system through which the group is bound to M′, or L″ is a moiety comprising boron or a member of Group 14 of the Periodic Table of the Elements, and optionally also comprising nitrogen, phosphorus, sulfur or oxygen, said L″ having up to 20 non-hydrogen atoms;
• Z is a moiety comprising boron or a member of Group 14 of the Periodic Table of the Elements, and also comprising nitrogen, phosphorus, sulfur or oxygen, said Z having up to 20 non-hydrogen atoms;
• X and X′ independently each occurrence are anionic ligand groups having up to 40 atoms exclusive of ligands containing an aromatic or conjugated dienyl π-system through which the group is bound to M and M′, respectively, or optionally two X groups or two X′ groups together form a divalent, C4-40 conjugated or nonconjugated dienyl ligand, optionally substituted with one or more hydrocarbyl, silyl, halocarbyl, or halohydrocarbyl groups, that together with M and M′, respectively, form a metallocyclopentene moiety;
• or further optionally, two X groups or two X′ groups together form a neutral, C4-40 conjugated or nonconjugated diene ligand, optionally substituted with one or more hydrocarbyl, silyl, halocarbyl, or halohydrocarbyl groups, that is π-bonded to M and M′, respectively;
• X″ independently each occurrence is a neutral ligating compound having up to 20 atoms, exclusive of neutral dienes;
• Q is a divalent anionic ligand group bound at one terminus to either Z or L and bound at the remaining terminus to either L′ or L″, said Q having up to 20 nonhydrogen atoms;
• and
• x, x′, and x″ are independently integers from 0 to 3;
• and
• 2) one or more activating cocatalysts;
• wherein activating cocatalyst component 2) causes both metal centers, M and M′, of the one or more bimetallic metal complexes 1) to be catalytically active for the polymerization of addition polymerizable monomers.