AN INVESTIGATION OF THE FIRST-ORDER SPIN-STATE TRANSITION IN FE(PHEN)(2)(NCS)(2) EXAFS AND INFRARED-SPECTROSCOPY

The structure of Fe(Phen)(2)(NCS)(2) has been examined across the firs t-order spin-state transition by EXAFS with full multiple scattering a nalysis. The EXAFS data at 298 K can be satisfactorily assigned to the high-spin state, but the analysis of the low-temperature data at 90 K is not entirely unequivocal, although consistent with the predominant presence of the low-spin state. That some proportion of the high-spin state remains at low temperatures, well below the first-order transit ion, is clearly evidenced in the infrared spectra, suggesting possible sublattice ordering.