Change in the coordination mode of nitrosyl groups:: Transformation of Pd4(μ-NO)4(μ-OCOCF3)4 into Pd3(NO)2(μ-OCOCF3)4(C6H5Me)2

The reaction of the tetranuclear complex of composition Pd-4(CO)(4)(CF3COO)(4) (I) with nitrogen monoxide (NO) was studied. The reaction involves the replacement of all the coordinated carbonyl groups with nitrosyl groups accompanied by redox transformations to give the tetranuclear complex Pd-4(NO)(4)(CF3COO)(4) (II). Complex II is structurally similar to the starting complex I, which was confirmed by elemental analysis, IR spectroscopy, and EXAFS. Complex II is unstable in aromatic solvents (benzene and toluene) and decomposes to form the trinuclear complex Pd-3(NO)(2)(CF3COO)(4)(TolH)(2) (III) and metallic palladium. X-ray diffraction analysis showed that the metal atoms in complex III form a linear chain in which each terminal atom is linked to the central atom via two bridging trifluoroacetate groups. The nitrosyl ligands are coordinated to the terminal palladium atoms in a bent end-on fashion. The scheme of the transformation of tetranuclear complex II into trinuclear complex III is proposed. This scheme was confirmed by quantum-chemical calculations.