Disclosed is a supported catalyst which is the reaction product of (a) a silylamine polymer having the general formula ##STR1## where each R is independently selected from alkyl from C.sub.1 to C.sub.6 or aryl from C.sub.6 to C.sub.10, R.sub.1 is a divalent aliphatic or aromatic group from C.sub.2 to C.sub.20, "m" is 1 to about 100, and "n" is 2 to about 500, with (b) an organometallic compound having the general formula Q--M--(X).sub.3 where Q is a stabilizing ligand, each X is independently selected from halogen, alkyl from C.sub.1 to C.sub.6, or dialkylamino from C.sub.1 to C.sub.6, M is zirconium, titanium, or hafnium and M is bonded to a nitrogen in said silylamine polymer, and the ratio nitrogens bondable to M in said silylamine polymer to M atoms is 1:1 to 3:1.