Magnetic Properties of Three Metal-organic Coordination Networks M(N$_{3})_{2}$(4,4'-bpy), M = Ni, Co, and Cu

All three newly synthesized metal-organic coordination networks M(N$_{3})_{2}$(4,4'-bpy) (M = Ni, Co, and Cu) crystallize in orthorhombic crystal system of the space group \textit{Cmmm} (No. 65). The M ions sites have octahedral geometries with slight distortions. Results of M(H) and $\chi $(T) for Ni(N$_{3})_{2}$(4,4'-bpy) and Co(N$_{3})_{2}$(4,4'-bpy) showed antiferromagnetic behavior, characterized by a cusp at T$_{N}$ = 3.5 K for Ni and T$_{N}$ = 4.0 K for Co in the $\chi $(T) data curves. Curie-Weiss fittings yielded $\mu _{eff}$ = 2.73 $\mu _{B}$ for Ni and $\mu _{eff}$ = 5.55 $\mu _{B}$ for Co. Hysteresis was detected in the M(H) data of Ni and Co. Results of M(H) and $\chi $(T) for Cu did not show any ordering or hysteresis. No sizable anomaly was observed in C(T) data for all compounds. Fisher classical spin linear chain model fit to the $\chi $(T) data yielded $\frac{\vert J\vert }{k_B }$ = 2.49 for Ni, and $\frac{\vert J\vert }{k_B }$ = 5.23 for Co. Both Quantum Statistical with spin $\raise.5ex\hbox{$\scriptstyle 1$}\kern-.1em/ \kern-.15em\lower.25ex\hbox{$\scriptstyle 2$} $ and High Spin Fisher Semiclassical Fit applied to spin $\raise.5ex\hbox{$\scriptstyle 1$}\kern-.1em/ \kern-.15em\lower.25ex\hbox{$\scriptstyle 2$} $ were performed to fit the $\chi $(T) data of Cu, and the latter had a better statistical results.