Thermal conversion of [Fe(phen)3](SCN)2 thin films into the spin crossover complex Fe(phen)2(NCS)2

Abstract

Heating the spin-crossover (SCO) complex FeII(phen)2(NCS)2 (phen = 1,10-phenanthroline) under high vacuum results in the formation of red films that have been identified as [FeII(phen)3](SCN)2 by IR, Raman, and UV-Vis spectroscopy. After annealing the red films to ∼140 °C under vacuum, purple (paramagnetic) films form and have been identified as Fe(phen)2(NCS)2 by SQUID magnetometry, X-ray photoelectron, Raman and IR spectroscopy. The Fe(phen)2(NCS)2 films exhibit a SCO transition at ∼180 K with a broadened transition temperature range between the high-spin and low-spin states (∼20 K) when compared to the bulk phase, which is ascribed to a broad distribution of molecular environments.