and lewis base compounds are employed in approximately stoichiometric amounts preferably in molar ratios based on amide compound to lewis base compound from 1 2 to 2 1 the quantity of solid lewis acid compound used is preferably from 2 1 to 10 to 1 more preferably from 4 1 to 6 1 based on group 4 metal amide compound as an illustration starting from hafnium tetrakis dimethylamide and excess alumina scavenger the resulting metal complex prepared according to the present invention in high yield and efficiency is the amide elimination conditions used in the present process include moderate temperatures from 0 to 100 u00b0 c especially from 25 to 75 u00b0 c reduced atmospheric or elevated pressures from 0 to 100 kpa preferably atmospheric pressure times from 1 minute to 10 days preferably from 10 minutes to 2 hours and use of an aliphatic or aromatic solvent preferably toluene or ethylbenzene the resulting complexes may be recovered by filtration extraction precipitation or other suitable technique the resulting group 4 metal complexes are activated to form the actual catalyst composition by combination with a cocatalyst preferably an aluminoxane a cation forming cocatalyst or a combination thereof and desirably employed to polymerize olefins or combinations of olefins especially ethylene propylene 1 butene 1 hexene 1 octene and mixtures thereof mixtures of the foregoing monomers with vinylaromatic monomers or conjugated or.