A ladder-type iron(<scp>ii</scp>) coordination polymer with enhanced spin-crossover behavior

Few spin-crossover materials with a 1D ladder-type structure have been reported. Previously, [Fe(Mebpt){Au(CN)2}]&#183;H2O (MebptH = 3-(5-methyl-2-pyridyl)-5-(2-pyridyl)-1,2,4-triazole) was made and shown to display gradual spin-crossover behaviour. In the current work, a new 1D iron(II) ladder-type compound, [Fe(bpt){Au(CN)2}] (bptH = 3-(2-pyridyl)-5-(2-pyridyl)-1,2,4-triazole), was produced and showed enhanced spin-crossover behavior. It showed an abrupt spin transition above room temperature with a 3 K hysteresis (T1/2↓ = 335 K and T1/2↑ = 338 K). The origin of its enhanced spin-crossover could be ascribed to a greater influence of supramolecular interactions over the electronic substituent effect.