1D polymeric copper(II) azido complexes. Synthesis, spectral and structural studies of [Cu(ethyl isonicotinate)(2)(N-3)(2)](n) and [Cu(methyl isonicotinate)(2)(NO3)(N-3)](n) complexes

Two new 1:2 polymeric complexes of copper(II) azide with ethyl isonicotinat e (1) and methyl isonicotinate (2) have been synthesized and characterized by spectroscopic and crystallographic methods. The polymeric structure of c omplex (1) features six coordinated copper centers, a pair of trans-coordin ated ligand molecules, and asymmetric mu(2)-1,1 and mu(2)-1,3-azido bridges resulting in a 1D chain structure. In complex (2), each copper atom which is located at an inversion center, is coordinated to a pair of trans ligand molecules, to the nitrogen atom of two mu-1,1-azido ligand and to an oxyge n atom of a bridging (mu-O,O') nitrogen group. The i.r., electronic and e.s .r. spectra of the complexes are reported.