Synthesis, spectral, magnetic and crystal structural characterization of two new copper(II) azido complexes: catena-[μ(N 3)Cu(pyridine) 3] n(PF 6) n and dimeric [Cu(4-ethylpyridine)(N 3) 2] 2

Abstract

Two new copper(II) azide complexes, namely [Cu(pyridine) 3(N 3)](PF 6) ( 1) and Cu(4-ethylpyridine)(N 3) 2 have been synthesized and characterized by spectroscopic and crystallographic methods. The structure of 1 contains a polymeric cation [Cu(pyridine) 3(N 3)] + and PF 6 − anion. Each copper atom, in the cation, is five coordinated by three nitrogen atoms from the pyridine ligands and two nitrogens from two μ(1,3) azide bridges forming a 1D structure. The geometry around each copper atom is best described as a square pyramid, and the azide group is asymmetric. The structure of complex 2 features dimeric molecules, copper atoms coordinated by three nitrogen atoms from two μ(1,1) azide bridges forming a Cu 2N 2 unit and a third azide group, the fourth site is occupied by the pyridine nitrogen. The third azide group links another two different copper atoms from an adjacent dimer at CuN distances of 2.729(12) and 3.206(12) Å. Thus this azide group functions as a μ(1,1,3) tridentate bridging ligand. The IR and electronic spectra are reported. Strong absorption bands due to N 3→Cu II CT transitions are observed in spectra of solids and solutions of both complexes. Magnetic susceptibilities at different temperatures of both complexes are presented and discussed.