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

Abstract

Three new copper(II) complexes of formulae [Cu(bpcam)(tcm)(H 2O)] · 2H 2O ( 1), [Cu(bpcam)(tcm)(H 2O)] ( 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 μ-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) Å. Magnetic susceptibility measurements of 3 in the temperature range 1.9–295 K show the occurrence of a weak intrachain antiferromagnetic interaction [ J = −0.39 cm −1 with the Hamiltonian being defined as H ˆ = - J ∑ i S ˆ i · S ˆ 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.