Metal complexes useful as olefin polymerization catalysts corresponding to the formula: ##STR1## wherein: L is a delocalized, .pi.-bonded group that is bound to M, containing up to 50 nonhydrogen atoms; M is a metal of Group 3, 4 or the Lanthanide series of the Periodic Table of the Elements; Z is a covalently bound, divalent substituent of up to 50 non-hydrogen atoms having the formula, --(ER.sub.2).sub.m --, wherein E independently each occurrence is carbon, silicon or germanium, R independently each occurrence is selected from the group consisting of C.sub.1-20 hydrocarbyl, and C.sub.1-20 hydrocarbyloxy, with the proviso that in at least one occurrence R is C.sub.1-20 hydrocarbyloxy, and m is an integer from 1 to 3; Y is a divalent ligand group comprising nitrogen, phosphorus, oxygen or sulfur, said Y containing up to 20 nonhydrogen atoms; X' is a neutral Lewis base ligand having up to 20 non-hydrogen atoms; X" independently each occurrence is a monovalent, anionic moiety selected from hydride, halo, hydrocarbyl, silyl, germyl, hydrocarbyloxy, amide, siloxy, halohydrocarbyl, halosilyl, silylhydrocarbyl, and aminohydrocarbyl having up to 20 non-hydrogen atoms, or two X" groups together form a divalent hydrocarbadiyl group; n is a number from 0 to 3; and p is an integer from 0 to 2.