Syntheses, crystal structures and magnetic properties of tricyanomethanide-containing bis(2-pyrimidylcarbonyl)amidate copper(II) complexes

Three new copper(II) complexes of formulae [Cu(bpcam)(tcm)(H2O)]center dot 2H(2)O (1), [Cu(bpcam)(tcm)(H2O] (2) and [Cu(bpcam)(tcm)](n) (3) [bpcam = bis (2-pyrimidylcarbonyl)amidate and tcm = tricyanomethanide] have been prepared and their structures determined by single crystal X-ray diffraction. Complexes 1 and 2 are mononuclear species where each copper atom is five-coordinated in a somewhat distorted square pyramidal environment with a tridentate bpcam ligand and a terminally bound tcm group building the basal plane and a water molecule in the apical position. Compound 3 is a uniform copper(II) chain where the [Cu(bpcam)](+) units are connected through single mu-1,5-tcm bridges which link one equatorial position at one copper atom with the apical position of the adjacent copper. The intrachain meal-metal separation in 3 is 7.678(2) angstrom. Magnetic susceptibility measurements of 3 in the temperature range 1.9-295 K show the occurrence of a weak intrachain anti ferro magnetic interaction [J = -0.39 cm(-1) with the Hamiltonian being defined as (H) over cap = -J Sigma(i)(S) over cap (i) center dot (S) over cap (i+1)]. This value of the magnetic coupling is analyzed through simple orbital symmetry considerations and compared with those observed through this bridge in other magneto-structurally characterized copper(II) complexes. (C) 2008 Elsevier Ltd. All rights reserved.