Nuclear inelastic scattering studies of a 1D- polynuclear spin crossover complex of Fe(II) urea-triazoles

The partial density of vibrational states (pDOS) of the low-spin isomer of the tosylate salt of [Fe{(N-Propyl)-N^′-(1,2,4-triazole-4-yl-urea)}₃]²⁺ was determined by nuclear inelastic scattering experiments performed at 8 K. The pDOS features a rich band structure from 320 to 500 cm⁻¹, characteristic of the low spin state of the complex. Density functional theory calculations (B3LYP/CEP-31G) were used to assign molecular modes to the experimentally observed peak in the pDOS.