New alternating ferro- and antiferromagnetic one-dimensional complexes. Synthesis, characterization, crystal structure, and magnetic properties of [M(4,4'-dimethylbipyridine)(N₃)₂](n) [M = Cu(II), Mn(II), Ni(II), Fe(II)]

The preparation, X-ray crystal structure, and magnetic properties of alternating 1,1- and 1,3-azido-bridged copper(II) complex [Cu(4,4'-dmbpy)(N₃)₂](n) (1, 4,4'-dmbpy = 4,4'-dimethylbipyridine) have been reported. It crystallizes in triclinic system, space group P1, a = 7.9903(1) Å, b = 9.3545(9) Å, c = 10.754(2) Å, α = 113.485(1)°, β = 101.399(1)°, γ = 101.897(1)°, Z = 2. The magnetic properties of 1 have been investigated in the temperature range 1.5-300 K. Alternating antiferromagnetic (-J = 191.0 cm^-1) interaction through a 1,3-N₃^- bridge and ferromagnetic (J = 297.1 cm^-1) interaction through a 1,1-N₃^- bridge are obtained for 1 by analyzing the magnetic susceptibility data with the Hamiltonian H = -JΣ(S(2i)S (2i-1) - αS(2i)S(2i+1)). It's derivatives ({Mn(4,4'-dmbpy)(N₃)₂}(n) (2), {Ni(4,4'-dmbpy)(N₃)₂}(n) (3), and {Fe(4,4'-dmbpy)(N₃)₂}(n) (4) and the heterometallic derivatives {NiMn(4,4'-dmbpy)₂(N₃)₄}(n) (5) and {CuMn(4,4'-dmbpy)₂(N₃)₄}(n) (6) have also been synthesized and characterized by electronic and IR spectra. The X-ray powder diffraction and the magnetic properties of 6 have also been discussed.