1D/2D coordination polymers of copper(II) having two superexchange pathways: syntheses, crystal structures and magnetic properties

Abstract

Two new polynuclear complexes of Cu(II), [(μ-1,1,3-N₃)₂{Cu₂(me₂tn)₂(N₃)₂}]_n (1) (me₂tn=2,2-dimethylpropane-1,3-diamine) and [Cu₂(μ-C₂O₄)(μ-N₃)(ipr₂en)₂]_n(ClO₄)_n (2) (ipr₂en=N,N′-di-isopropylethane-1,2-diamine) have been synthesized and structurally characterized by X-ray crystallography. The crystal structure of 1 displays a 2D network in which distorted octahedral copper(II) centers, chelated by a me₂tn ligand and bound to a terminal azide, are connected through μ-1,1,3 bridging azide anions. The structure of 2 shows 1D chains comprising alternating [(ipr₂en)Cu-Ox-Cu(ipr₂en)] units and end-to-end azide ligand. The chains on mutual H-bonding interaction through ClO₂^-, give rise to a 2D supramolecular architecture. The magnetic data of complexes were recorded in the temperature range, 300–2 K. In case of complex 1, the magnetic data are consistent with a ferromagnetic interaction through the end-on azide bridge (J_FM=10 cm^-1) and a weak antiferromagnetic interaction (zj=−0.8 cm^-1) between the ferromagnetically coupled dimers and an average g-value of 2.05. The susceptibility data of 2 were fitted using an alternating AF–AF chain spin 1/2 law which leads to the following parameters J_oxalate=−180 cm^-1, J_azide=−43 cm^-1 and g=2.25 cm^-1. Two new azido-briged complexes of Cu(II) are synthesized and characterized by X-ray single crystal structure and low temperature magnetic study. Both the complexes have two different superexchange pathways which result two types of magnetic interactions.