Synthesis, Structural Characterization, Magnetic Behavior, and Single Crystal EPR Spectra of Three New One-Dimensional Manganese Azido Systems with FM, Alternating FM-AF, and AF Coupling

Reaction of sodium azide with manganese(II) and pyridine derivatives such as 2-bzpy, 3-bzpy, and 3,5lut (2-benzoylpyridine, 3-benzoylpyridine, and 3,5-dimethylpyridine, respectively) led to the one-dimensional systems cis-[Mn(2-bzpy)(N₃)₂]_n (1), trans-[Mn(3-Bzpy)₂(N₃)₂]_n (2), and cis-[Mn(3,5lut)₂(N₃)₂]_n (3). Compound 1 crystallizes in the P2₁/n group:  a = 14.413(4) Å, b = 16.157(4) Å, c = 18.478(5) Å, and Z = 12. Compound 2 crystallizes in the C2/c group:  a = 14.179(5) Å, b = 9.698(4) Å, c = 34.351(12) Å, and Z = 8. Compound 3 crystallizes in the P2₁/n group:  a = 13.552(6) Å, b = 7.730(3) Å, c = 16.554(6) Å, and Z = 4. Structural determination shows a chain with double μ_1,1 azido bridges for 1, an alternating system with double μ_1,1 and μ_1,3 azido bridges for 2, and finally a chain with double μ_1,3 azido bridges for 3. Susceptibility data show ferromagnetic coupling for 1, antiferromagnetic coupling for 3, and alternating ferro−antiferromagnetic interactions for 2. EPR data measured on powdered samples and single crystals show the ideal Heisenberg narrowing angular dependence for the three kinds of coupled systems and an increasing dipolar broadening mechanism in the order 3 < 2 < 1 according to the decreasing Mn···Mn intrachain distances.