Ligand Conformation Enforces Trigonal Bipyramidal Coordination Geometry in a New Dinuclear Bis(pyrazolato)-Bridged Copper(II) Complex:  Synthesis, Crystal Structure, and Properties of [Cu(Npy2pz)]2(ClO4)2·2CH3CN

• Published in: Inorganic chemistry 2005-10, Vol.44 (22), p.7860-7865
• Main Authors: Tanase, Stefania, Koval, Iryna A, Bouwman, Elisabeth, de Gelder, René, Reedijk, Jan
• Format: Article
• Language: English
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/ic050793w

The reaction of Cu(ClO4)2·6H2O with the new tripodal ligand HNpy2pz (N-bis[(pyridin-2-yl)methyl][1H-pyrazol-3-yl)methyl]amine) in the presence of 1 equiv of triethylamine results in the formation of a doubly pyrazolato-bridged dicopper(II) complex, [Cu(Npy2pz)]2(ClO4)2·2CH3CN (1). The crystal structure of 1 was determined by X-ray crystallography and was found to consist of two nearly identical discrete dinuclear molecules with bis(pyrazolato) bridges. The copper(II) ion has a trigonal bipyramid geometry achieved by the coordination of an aliphatic nitrogen, two pyridine moieties, and two pyrazolato nitrogens. Variable temperature-dependent magnetic data show that antiferromagnetic interactions operate in 1 as a result of the binding angle of the pyrazolato bridge. In solution, the stability of the dinuclear cation, [Cu(py2pz)]2 2+, is highly dependent on the concentration, as indicated by ESI-MS, ligand field, cyclic voltammetry, EPR, and 1H NMR studies.