First Iron(II) Spin-crossover Complex with an N5S Coordination Sphere

A novel dinuclear iron(II) complex [{Fe(py(3)COH)(NCS)(mu-NCS)}(2)](PrOH)(2) was prepared. Each Fe ion is coordinated with three N atoms from tridentate tris(2-pyridyl)methanol (py(3)COH) and two N and one S atoms from NCS- coligand. It showed a one-step gradual spin-crossover at T-1/2 = 207K. This compound is the first spin-crossover material having an FeN5S coordination structure.