Formation of n-hexane from methylcyclopentane via a metallacyclobutane intermediate at step sites of Pt surfaces: Mechanism from first-principles calculations

With periodic density functional theory calculations, we examined the ring opening of methylcyclopentane to n-hexane via an αγ-adsorbed metallacyclobutane intermediate over the stepped model surface Pt(3 2 2). The crucial barrier of C-C scission along this pathway was calculated as low as 79 kJ mol^-1, that is, about 20 kJ mol^-1 lower than the value for analogous steps via ααββ-adsorbed intermediates on the way to 2- or 3-methylpentane on Pt(2 1 1). Thus, at step sites of Pt surfaces, formation of (unbranched) n-hexane seems to be more favorable than formation of branched hexanes.