The Uninodal 3D 1,2,4‐Triazolate Frameworks 3 ∞ [ M 5 Cl 3 (Tz) 7 (TzH) 2 ], M = Mn, Fe

A complex framework structure is observed as product of reactions of either MnCl 2 or FeCl 2 together with the small N ‐heterocycle 1H‐1,2,4‐triazole, triethylamine, and pyridine from reactions in sealed ampoules under solvothermal conditions. 3 ∞ [M 5 Cl 3 (Tz) 7 (TzH) 2 ]·NEt 3 (HCl) 0.5 , M = Mn, Fe, TzH = 1H‐1,2,4‐triazole, form as 3D coordination polymers with NEt 3 HCl intercalated into the pores of the structure. The framework is constituted by three different crystallographic sites for the divalent transition metal ions coordinated by chloride anions, and N atoms of triazolate, as well as triazole ligands. Removal of the intercalated salt at elevated temperatures leads to decomposition of the framework structures. The Fe‐containing framework shows a thermochromic effect for T > 120 °C between pink‐red (RT) and a sand tone.