Crystal structures and magnetic properties of the mono-µ-halogeno-bridged copper(II) chains Cu(pcpci)X [pcpci =N-(2′-pyridylcarbonyl)pyridine-2-carboximidate, X = Cl or Br]

Abstract

Compounds Cu(pcpci)Cl (1) and Cu(pcpci)Br (2)[pcpci =N-(2′-pyridylcarbonyl)pyridine-2-carboximidate] are isostructural and crystallize in the monoclinic space group Pc with two formula units in cells of dimensions [(1)/(2)]: a= 3.963(2)/3.888(3), b= 8.48(3)/8.641(3), c= 18.21(12)/17.944(11)Å, and β= 94.9(2)/92.63(6)°. The crystal and molecular structure of (2) has been determined by X-ray diffraction methods. Least-squares refinement of 1 351 reflections with I > 2.5σ(I) and 189 parameters gave a final R′= 0.065. The complex exhibits a chain arrangement built up of Cu(pcpci)Br units linked through the bromine atoms. The copper(II) ions are five-co-ordinate and the co-ordination geometry is near square pyramidal. Magnetic susceptibility measurements were analyzed in terms of the Heisenberg model yielding antiferromagnetic exchange interactions of J(1)=–0.4 and J(2)=–0.8 cm^–1. These values are discussed on the basis of the structural features and correlated with published magnetostructural data.