Quantitative 13 C{ 1 H} NMR spectra of the oils in C6D6 are shown in Figure . Most spectra in Figure contain signals that are characteristic of regioirregular errors encountered in polypropylene synthesis, or copolymerization reactions of ethylene and propylene. These results indicate that some degree of chain-straightening occurs during hydrogenolysis with 1. All 13 C{ 1 H} NMR spectra contain signals for ethyl, propyl, and/or butyl end groups. Integration of the end groups relative to the rest of the 13 C{ 1 H} NMR signals gives the Mn of the oils reported in Table . The matrix assisted laser desorption ionization (MALDI) mass spectrum of extracted oil from Entry 1 contains a broad distribution of products centered at m/z of 538 (~10 C3H6 units *Ag + ) that is close to Mn obtained from integration of 13 C{ 1 H} NMR signals. GCMS data of the oil is complex, but also supports the formation of a distribution of branched alkanes. These trends hold for all oils isolated in Table , though some oils fragment in the MALDI MS. The proposed key steps in iPP hydrogenolysis mediated by 1 are shown in Figure and account for the end groups obtained in hydrogenolysis of iPP and deuterium incorporation shown in eq 2. Hf-H + undergoes s-bond metathesis with a primary or secondary C-H bond in iPP to form Hf-R + . b-Alkyl elimination forms Hf(R)(olefin) + intermediates that are hydrogenated by H2. The exact sequence of steps to form initially isotactic alkanes from Hf(R)(olefin) + is not clear currently, but probably involves olefin dissociation to facilitate hydrogenolysis of Hf-R + by a s-bond metathesis reaction prior to olefin hydrogenation.