Preparation, crystal structure and magnetic properties of di-2-pyridylamine (dpa) copper(II) complexes [Cu(dpa)(N-3)(2)](n) and [Cu-2(dpa)(2)(NCO)(4)]

摘要

The preparation, crystal structures and magnetic properties of two copper([ 1) complexes with di-2-pyridylamine (dpa) as end-cap ligand and azide (1) and cyanate (2) as bridging groups, [Cu(dpa)(N-3)(2)](n) (1) and [Cu-2(dpa)(2)(NCO)(4)] (2), are reported. Compound 1 consists of uniform chains of copper(II) ions bridged by single mu-1, 1-azido groups whereas that of compound 2 is made up of centrosymmetric dicopper(II) units with double mu-1, 1-N-cyanate bridges, the other two cyanate groups acting as terminal ligands. The copper atoms in 1 and 2 are five-coordinated with two nitrogen atoms of a bidentate dpa ligand (1 and 2), one nitrogen atom from a terminally bound azide (1)/cyanate (2) and two other nitrogens from two azide (1)/cyanate (2) bridges building intermediate square pyramidal/trigonal bipyramidal (1) and distorted square pyramidal (2) surroundings. The values of the copper-coppcr separation through the double end-on azido (1) and cyanato (2) bridges are 3.8556(4) and 3.5154(5) angstrom, respectively. Variable-temperature magnetic susceptibility measurements show the occurrence of weak magnetic interactions in both complexes being antiferromagnetic in 1 [J = -4.60 cm(-1) the Hamiltonian is defined as (H) over cap = -J Sigma(i)(S) over cap (i) . (S) over cap (i+1)] and ferromagnetic in 2 [J = +3.14 cm(-1) with (H) over cap = -J (S) over cap (1) . (S) over cap (2)]. The magnitude and nature of these magnetic interactions are discussed in the light of the respectives structures and they are compared with those reported for related systems.