A new Cu/Zn carboxylato-bridged 1D polymer: Direct synthesis, X-ray structure and magnetic properties

A new complex [Cu2Zn(O2CMe)(6)(NH3)(2)](n) was isolated as an unexpected product in an open-air synthesis of a mixed-metal compound using zero-valent copper, zinc oxide and ammonium acetate in the presence of 2-diethylaminoethanol in acetonitrile solution. Its structure consists of Cu-2(O2CMe)(4) units situated on crystallographic inversion centres and Zn(NH3)(2)(O2CMe)(2) units on crystallographic 2-fold axes. One O atom of each of the O2CMe groups is attached via Zn bridges to the Cu atoms of the dimeric Cu-2(O2CMe)(4) unit forming a 1D polymer in the bc direction. The polymer is not linear, with the dihedral angles between successive Cu-Cu vectors being 48.9 degrees. Within the Cu-2(O2CMe)(4) units the Cu center dot center dot center dot Cu distance is 2.675(2) angstrom and the angles between the O2CMe planes are 88.8(5)degrees. The magnetic properties have been analyzed using the Hamiltonian (H) over cap = J (S) over cap (1)(S) over cap (2) with J = 286 cm(-1) and g = 2.13. High-field EPR spectra showed both the exchange-coupled copper pair and non-interacting copper(II) ions. The presence of the latter species was explained as an effect of zinc atoms occupying a fraction of the copper sites. (C) 2011 Elsevier B.V. All rights reserved.