Synthesis, spectral, magnetic and crystal structural characterization of two new copper(II) azido complexes: catena-[mu(N-3)Cu(pyridine)(3)](n)(PF6)(n) and dimeric [Cu(4-ethylpyridine)(N-3)(2)](2)

Two new copper(II) azide complexes, namely [Cu(pyridine)(3)(N-3)](PF6) (1) and Cu(4-ethylpyridine)(N-3)(2) have been synthesized and characterized by spectroscopic and crystallographic methods. The structure of I contains a p olymeric cation [Cu(-pyridine)(3)(N-3)](+) and PF6- anion. Each copper atom , in the cation, is five coordinated by three nitrogen atoms from the pyrid ine ligands and two nitrogens from two mu (1,3) azide bridges forming a ID structure. The geometry around each copper atom is best described as a squa re pyramid, and the azide group is asymmetric. The structure of complex 2 f eatures dimeric molecules, copper atoms coordinated by three nitrogen atoms from two mu (1,1) azide bridges forming a Cu2N2 unit and a third azide gro up, the fourth site is occupied by the pyridine nitrogen. The third azide g roup links another two different copper atoms from an adjacent dimer at Cu- N distances of 2.729(12) and 3.206(12) Angstrom. Thus this azide group func tions as a mu (1,1,3) tridentate bridging ligand. The IR and electronic spe ctra are reported. Strong absorption bands due to N-3 --> Cu-II CT transiti ons are observed in spectra of solids and solutions of both complexes. Magn etic susceptibilities at different temperatures of both complexes are prese nted and discussed. (C) 2001 Published by Elsevier Science Ltd.