Synthesis,structure and properties of a monomeric copper(II) complex with a multidentate pyridylpyrazole ligand

摘要

Using a potentially multidentate ligand,L~6 (2,6-bis[3-(2'-pyridyl)pyrazol-l-ylmethyl]pyridine),having five N donor sites,a new mononuclear copper(II) compound,[Cu(L~6)][C1O4]2,has been synthesized.X-ray crystallographic analysis reveals that it is in the monoclinic space group C2/c with all five donor sites coordinating with copper(II) to provide a distorted trigonal bipyramidal coordination environment around copper.Closer inspection of crystal packing diagram reveals the formation of 2D network structure,assembled via two types of noncovalent interactions.Notably,pi…pi interactions between n electron cloud of pyridine rings of pyridylpyrazole unit lead to the formation of a linear chain,which is then connected to another chain via C-H ' 7t interactions involving pyridyl C-H (4-position) of central pyridine ring of L6 and 7t electron cloud of pyridine ring of pyridylpyrazole unit in a bifurcated fashion.Coordination geometry in solution (MeCN) state has been assessed by absoiption and EPR spectroscopy.Cyclic voltammetry reveals inherent flexibility of the ligand system to allow stabilization of copper(I) oxidation state.