Synthesis, spectral and structural characterization of two polymeric 1:1 complexes of 2,3-dimethylpyridine and 5-ethyl-2-methylpyridine with copper(II) azide; Cu(2,3-dimethylpyridine) (N-3)(2) and Cu(2-methyl-5-ethylpyridine) (N-3)(2)

Two new 1:1 ligand complexes of copper(II) azide with disubstituted pyridine ligands, namely catena-di-mu(1,3)-azido-[di-mu(1,1)-azidobis(2,3-lutidine) dicopper(II)] (1) and catena-di-mu(1,1)-azido[di-mu(1,1)-azidobis(2-methyl-5-ethylpyridine)dicopper(II)] (2), have been synthesized and characterized by spectroscopic and X-ray crystallographic methods. The polymeric complex 1 features monodentate 2,3-lut ligands, centrosymmetric di-mu(1,1)-azido-bridged Cu2N2 rings, distorted square-pyramidal copper(II) coordination geometry and di-mu(1,3)-azido bridges which link the centrosymmetric binuclear Cu-2(2,3-lut)(2)(N-3)(2) moieties to form sheets within the ab plane. In the monoclinic crystals of complex 2, the copper(II) centres are pentacoordinated via N(11), N(21), N(11b) and N(21a) from the azido ligands [Cu-N distances 1.971(5)-2.286(5) Angstrom] and N(1) from the organic molecule at a Cu-N bond length of 2.001(5) Angstrom. Both azido ligands function as mu(1,1) bridges to form chains of polyhedra along the short a-axis of the unit cell. The IR absorption spectra reveal that each of these complexes contains two independent azide ligands. The solid and solution electronic spectra of complexes 1 and 2 show at least three and two strong absorption bands, respectively, associated with N-3(-) --> Cu-II charge transfer transitions. The EPR spectra of powder samples and DMSO solutions at room temperature were recorded and are discussed. Copyright (C) 1996 Elsevier Science Ltd