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Al in: A new strategy was introduced to modify the electronics and steric hindrance of the Pd(II) ion in order to change its reactivity towards benzene hydroxylation. In trifluoroacetic acid, free Pd(II) ions provide dominantly biphenyl, with phenol as minor product. Ligation of bpym to the Pd(II) ion results in its deactivation with regard to benzene functionalization. The addition of the redox inactive Al(III) ion to the Pd(II)(bpym) complex recovers its catalytic activity, and alters the reactivity of Pd(II) ion from benzene coupling to hydroxylation.

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A simple, efficient method for oxidation of primary and secondary alcohols to the corresponding aldehydes and ketones has been developed. Using RuCl 3 /Et 3 N as catalyst, the oxidation of benzyl alcohol with oxygen could be achieved with 332 h À1 turnover frequency in the absence of solvent. The influence of versatile N-containing additives on the catalytic efficiency has been discussed. The presence of minor water would substantially promote the catalytic efficiency, and its role in catalysis has been investigated in detail. The insensitive Hammett correlations of the substituted benzyl alcohols, the normal substrate isotope effect (k H /k D = 3.5 at 335 K), and the linear relationship between O 2 pressure and turnover frequency imply that the reoxidation of the Ru(III) hydride intermediate to the active species shares the rate-determining step with the hydride transfer in the catalytic cycle.

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