With Fe/SiO2, Ru/SiO2 and Os/SiO2, any acyclic olefin (e.g. ethylene, propylene or isobutene) homologates at 200 - 300°C to yield higher and lower olefins with the simultaneous formation of methane. The reaction is catalytic when H2 is present. The main features of such reactions are reported, i.e. conversions, turnover numbers, product distribution, effect of contact time on the selectivity for α-olefins and branched olefins. The results are compared with those obtained in Fischer-Tropsch syntheses. It is shown that the mode of C-C bond formation for the hydrocondensation of CO or olefin homologation is the same. Two possible mechanisms are discussed to account for the data. These mechanisms assume either the insertion of a carbene into a metal-alkyl bond or the attack of a carbene on a coordinated olefin.
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