Transition Metal Activation of Aldehydes: Platinum Metal Derivatives of O-Diphenylphosphinobenzaldehyde

The reactivity of aldehydes toward metal ions remains an obscure area of coordination chemistry despite the widespread dependence of the preparations and reactions of the formyl group on metal ion catalysis in industrial synthesis where aldehydes are prepared via palladium catalyzed oxidation and the cobalt and rhodium catalyzed hydroformylation of olefins.¹Hydrogenations,² hydrosilvlations,³ and decarbonylations.¹ of the formyl group proceed via platinum metals catalysis; additionally, the hvdroacylation of olefins is promoted by rhodium⁵ and ruthenium⁷ compounds. The prevailing interest in the transition metal induced scission and formation of C-H and C-C bonds⁸ renders our synthetic and mechanistic results on these processes especially timely. We find that o-diphen-ylphosphinobenzaldehyde⁹ (1, abbreviated PCHO) stabilizes intermediates in the reactions of the aldehyde group with several metal ions which reveal new mechanistic information concerning metal-hydrocarbon interactions.