McKervey-Rooney-Samman mechanism

Muller and Gault proposed (57) an adsorbed cyclopropane-like intermediate (Scheme VIIIB). The McKervey-Rooney-Samman mechanism involves a n complex like adsorption of two carbon atoms (88) (Scheme Vine). 

A monotonic decrease of benzene yield from methylpentanes is observed as a function of the hydrogen pressure over both metals (27a, 91a). The intermediates of bond shift type dehydroisomerization are likely to be unsaturated. This points to the McKervey-Rooney-Samman mechanism (55). This pathway obviously has a higher energy barrier over platinum than over palladium as compared with the aromatization of -hexane. This is reflected also by the similar aromatization selectivity (iS r) values of -hexane and methylpentanes over palladium (Table IV). 

The facile isomerization of strained bridged molecules was inconsistent with the involvement of triadsorbed species 15. Instead, a a-alkyl adsorbed species was proposed. Its further transformation leads to a it-complex-like species (17) with a three-center, two-electron bonding with its simultaneous attachment to the surface152,157 (McKervey-Rooney-Samman mechanism) ... 

Fig. 2. Mechanisms of bond-shift isomerization on metal catalysts, (a) Anderson-Avery mechanism (63). (b) Muller-Gault mechanism for isomerization of neopentane on Pt (64). (c) McKervey-Rooney-Samman mechanism (69). (d) Muller-Gault mechanism of isomerization of isobutane on Pd (64). (e) Clarke-Rooney mechanism (46). (f) Garin-Gault mechanism (65).

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