Palladium nitrosyl carboxylate clusters: Synthesis and reactivity. X-ray structures of Pd4(μ-CO)2(μ-NO)(μ-RCO2)5 (R = iPr, iBu)

New palladium nitrosyl carboxylate complexes Pd8(CO)4−m(NO)m(NO2)4(RCO2)8 (m = 2, 4) were obtained by the treatment of palladium carbonyl carboxylates clusters cyclo-Pdn(μ-CO)n(μ-RCO2)n (n = 6) (1) with gaseous nitrogen monoxide. These complexes are the products of CO substitution in early described Pd8(CO)4(NO2)4(RCO2)8 clusters. By adding an excess of corresponding acid to reaction mixture Pd4(CO)2(NO)(RCO2)5 complexes were obtained, their structures were determined by X-ray diffraction analysis. These clusters are intermediate products of transformation of 6-nuclear initial clusters into various 8-nuclear complexes. This fact demonstrates that carboxylate ligands can be used as stabilizers for intermediate unstable polynuclear palladium compounds.