Polynuclear pyrazolato complexes. Synthesis, chemical reactivity and crystal structures of [{Pd(dmpz)2(Hdmpz)2}2] and [{PdAg2(dmpz)4}2](Hdmpz = 3,5-dimethylpyrazole)

Abstract

The dinuclear complex [{Pd(dmpz)₂(Hdmpz)₂}₂](Hdmpz = 3,5-dimethylpyrazole) has been synthesized and its solid-state structure determined by X-ray methods. Each dimeric molecule, of idealized 422 symmetry, possesses four strong intramolecular hydrogen bonds, equalizing the Hdmpz and dmpz ligands. The complex has been treated with AgNO₃ and [Cu(MeCN)₄]BF₄, in search of heterobimetallic derivatives; [{PdCu₂(dmpz)₄}₂] and [{PdAg₂(dmpz)₄}₂] species have been isolated. The latter, characterized by X-ray methods, is a non-bonded octahedral cluster (trans Pd₂Ag₄) bridged by eight dihapto dmpz ligands, thus formally deriving from its precursor by substitution of four H⁺ by Ag⁺ ions. This increases the Pd⋯Pd distance from 3.746(1) to 5.160(1)Å, and slightly changes the ligand conformation.