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.

Graphical abstractThe interaction of Pd6(CO)6(RCO2)6 with gaseous NO was investigated and new palladium nitrosyl complexes Pd8(CO)4−x(NO)x(NO2)4(RCO2)8 (x = 2, 4) were obtained. The addition of an excess of corresponding carboxylic acids allowed isolating of Pd4(CO)2(NO)(RCO2)5 compounds, which demonstrates an ability of carboxylate ligand to stabilize intermediate products of transformations of palladium clusters.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► The substitution of CO-ligands in clusters Pd8(CO)4(NO2)4(RCO2)8 in the reaction with NO was observed. ► New palladium nitrosyl clusters Pd8(CO)4−m(NO)m(NO2)4(RCO2)8 (m = 2, 4) were obtained. ► First palladium nitrosyl-carbonyl clusters Pd4(CO)2(NO)(RCO2)5 were structurally characterized. ► The ability of carboxylate groups to stabilize intermediate palladium clusters was shown.