POLYNUCLEAR PYRAZOLATO COMPLEXES - SYNTHESIS, CHEMICAL-REACTIVITY ANDCRYSTAL-STRUCTURES OF [(PD(DMPZ)(2)(HDMPZ)(2))(2)] AND [(PDAG2(DMPZ)(4))(2)] (HDMPZ=3,5-DIMETHYLPYRAZOLE)

The dinuclear complex [{Pd(dmpz)(2)(Hdmpz)(2)}(2)] (Hdmpz = 3,5-dimeth ylpyrazole) has been synthesized and its solid-state structure determi ned 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 [C u(MeCN)(4)]BF4, in search of heterobimetallic derivatives; [{PdCu2(dmp z)(4)}(2)] and [{PdAg2(dmpz)(4)}(2)] species have been isolated. The l atter, characterized by X-ray methods, is anon-bonded octahedral clust er (trans Pd2Ag4) bridged by eight dihapto dmpz ligands, thus formally deriving from its precursor by substitution of four H+ by Ag+ ions. T his increases the Pd ... Pd distance from 3.746(1) to 5.160(1) Angstro m, and slightly changes the ligand conformation.