New palladium nanoclusters. Synthesis, structure, and catalytic properties

The reduction of palladium(II) carboxylates Pd-3(OCOR)(6) (R = Me, Et, CHMe2, CMe3) with hydrogen in alcohol solutions containing 1,10-phenanthroline (phen) and subsequent oxidation with oxygen gave new palladium nanoclusters, mainly particles with a nearly spherical metal core and an average size of 18 Angstrom. Based on elemental analysis, NMR, X-ray photoelectron spectroscopy, and EXAFS, nanoclusters were described by the idealized formula Pd(147)phen(32)O(60)(OCOR)(30). The specimens contained up to similar to25%, smaller 55-atomic Pd clusters with a similar to10 Angstrom metal core. New nanoclusters catalyze hydrogenation of alkynes and alkenes, reduction of nitriles with formic acid, oxidation of aliphatic and benzylic alcohols, oxidative esterification of ethylene and propylene, and disproportionation of benzyl alcohol into toluene and benzaldehyde.