Heat capacity measurements of 2 displayed a first-order phase transition associated with a T1/2 temperature of 265 K associated with HS to LS conversion, which was further investigated by variable temperature IR as well as Raman spectroscopies. The Raman and IR studies focused on the  NC stretching vibration coming from the NCS -ligand, which was detected at 2120 cm -1 (LS) and 2075 cm -1 (HS) depending upon the spin state of the Fe(II) center.