Our hypothesis is that typical Ziegler-Natta polymerization catalysts could react similarly as shown in Figure . Typical Zielger-Natta catalysts contains a Group IV metallocene 6 or post-metallocene pre-catalyst that is activated 8 to form LnM-R + (M = Ti, Zr, Hf; R = H, alkyl) that coordinates and inserts 9 olefin to grow the polymer. These steps are shown in Figure for the formation of isotactic polypropylene (iPP) through the common 1,2-insertion of propylene into LnM-R + . 11 Chain transfer releases the polymer from the metal to regenerate catalytically active LnM-R + . In the absence of exogenous alkylaluminium activator the most common chain transfer pathways are b-H elimination to generate LnM-H + and iPP with vinylidene end groups, or b-Me elimination to generate LnM-Me + and iPP with vinyl end groups. The outcome of this reaction depends on sterics at the metal center. Sterically open Cp2Hf-CH3 + terminates propylene polymerization by b-H elimination, but sterically bulky Cp*2Hf-CH3 + favors chain termination by b-methyl elimination. The b-Me elimination shown in Figure is, in essence, a signature of b-alkyl elimination required for C-C hydrogenolysis shown in Figure . Cationic Hf-H + generated in solution are known to engage in s-bond metathesis reactions with silanes, analogous to the d 0 metal hydrides shown in Figure that are proposed to activate C-H bonds to from M-R and H2. Therefore, cationic organometallic complexes formed in typical Ziegler-Natta catalysts would be expected to show activity in reactions that digest polyolefins in the presence of H2. Catalysts of this type are more desirable than those shown in Figure . LnM-R + form readily in solution or on solid supports in common industrial compositions used in olefin polymerization reactions. This paper describes formation of Cp2Hf-CH3 + sites on a weakly coordinating oxide 16 that catalyze hydrogenolysis of iPP.