The use of trans-4-cotininecarboxylate to construct a polymeric copper(II) azido complex: Hydro(solvo)thermal synthesis, structure and magnetic properties

Abstract

A new pyridyl-carboxylate ligand, the anion of trans-4-cotininecarboxylic acid, H L, 1, has been used to prepare a new polymeric copper(II) complex, [Cu LN 3] 2 n , 2, based on a [Cu LN 3] 2 dimeric building block. The single crystal structures of both 1 and 2 have been determined and 1 has been found to be in its zwitterionic configuration. The structure of 2 is a one-dimensional tape-like polymeric structure based on an end-on azido-bridged binuclear [Cu 2N 3] 2 backbone moiety. Magnetic studies reveal that 2 is close to paramagnetic from 2 to 300 K with a Curie constant of 1.094 emu K/mol, a Weiss temperature of 0.73 K and a corresponding μ eff of 2.09 μ B. A fit of χ MT for 2 with S 1 = S 2 = ½, yields g = 2.441(6), J = −0.49(3) cm −1, zJ = −0.38(2) cm −1 and N( α) = 0.00053(12) emu/mol, a fit that indicates the presence of both very weak intramolecular intrachain antiferromagnetic exchange coupling within the one-dimensional tape-like chains and very weak interchain antiferromagnetic exchange coupling between these chains.