Structure, magnetic properties and DFT calculations of azido-copper(II) complexes with different azido-bonding, nuclearity and dimensionality

Abstract

Four bridged-azido Cu(II) complexes were synthesized and structurally characterized: [Cu-2(Et(3)en)(2)(mu(1,1)-N-3)(2)(N-3)(2)] (1), [Cu-2(ip(2)en)(2)(mu(1,1)-N-3)(2)(N-3)(2)] (2), catena-[Cu-2(Et(2)Meen)(2)(mu(1,3)-N-3)(3)]ClO4 (3) and catena-[Cu(ambza)(mu(1,1,3)-N-3)(2)] (4), where Et(3)en = N, N, N'-triethyl-1,2-diaminoethane; ip(2)en = N, N'-diisopropyl-1,2-diaminoethane; Et(2)Meen = N, N-diethyl-N'-methyl-1,2-diaminoethane; and ambza = 2-aminobenzylamine. Single crystal X-ray crystallography revealed that complexes 1 and 2 are dinuclear with doubly bridged mu(1,1)-N-3, whereas complexes 3 and 4 constitute polymeric species with an alternative sequence of single and double mu(1,3)-N-3 bridges for 3 with a 1D chain, and triple mu(1,1,3)-bridging azide in 4 with a 2D extended structure. Variable temperature magnetic susceptibilities over the temperature range of 2-298 K revealed a weak antiferromagnetic coupling (J = -1.8 cm(-1)) for 1, and a ferromagnetic coupling with J values of 7.0 and 7.7 cm(-1), respectively, for complexes 2 and 4, respectively. Compound 3 shows a new topology for Cu(II) alternating chains [Cu(1)(mu(1,3)-N-3)(2)Cu(1')]-(mu(1,3)-N-3)-[Cu(2')(mu(1,3)-N-3)(2)Cu(2 '')]-(mu(1,3)-N-3)-[Cu(1)(mu(1,3)-N-3)(2)Cu(1')]-... Three different coupling constants were obtained through a fitting procedure and by DFT calculations.