Synthesis, spectral, magnetic and crystal structural characterization of two new copper(II) azido complexes: catena-[#mu#(N_3)Cu(pyridine)_3]_n(PF_6)_n and dimeric [Cu(4-ethylpyridine)(N_3)_2]_2

摘要

Two new copper(II) azide complexes, namely [Cu(pyridine)_3(N_3)](PF_6) (1) and Cu(4-ethylpyridine)(N_3)_2 have beensynthesized and characterized by spectroscopic and crystallographic methods. The strucure of 1 contains a polymeric cation [Cu(pyridine)_3(N_3)]~+ and PF_6~- anion. Each copper atom, in the cation, is five coordianted by three nitrogen atoms from the pyridine ligands and two nitrogens from two #mu#(1,3) azide bridges forming a 1D structure. The geometry around each copper atom is best dexribed as a square pyramid, and the azide group is asymmetric. The structure of complexes 2 features dimeric moleucles, copper atoms coordianted by three nitrogen atoms from two #mu#(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) A. Thus this azide group functions as a #mu#(1,1,3) tridentate bridging ligand. The IR and electronic spectra are reported. Strong absorption badns 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.