Mechanistic investigation on the hydrogenation of imines by [p-(M(e)2CH)C6H4Me]RuH(NH2CHPhCHPhNSO2C6H4-p-CH3). Experimental support for an ionic pathway

The need for acidic activation in the stoichiometric hydrogenation of benzyl-[1-phenyl-ethylidene]-amine (6a) or [1-(4-methoxyphenyl)- ethylidene]- methyl-amine (6b) by Noyori's catalyst [p-(Me2CH)C6H4Me] RuH(NH2CHPhCHPhNSO2C6H4-p- CH3) ( 2) is inconsistent with the proposed concerted mechanism and supports an ionic mechanism.