Raman spectroscopy of the high- and low-spin states of the spin crossover complex Fe(phen)(2)(NCS)(2): an initial approach to estimation of vibrational contributions to the associated entropy change

Raman spectra of the spin-crossover complex Fe(phen)(2)(NCS)(2) in the soli d state have been recorded at 785 nm as a function of temperature to invest igate the contribution of intramolecular vibrations to the entropy change, Delta S, associated with spin crossover. The modes of major interest for es timating the contribution lie in the range 100-500 cm(-1), where the larges t qualitative changes with temperature in the Raman spectra were observed. Analysis of these data, with the working assumption of an average frequency in this range as representative of the 15 distortion modes of an idealised FeN6 octahedron, leads to the conclusion that the intramolecular vibration s represent a primary contribution to the total Delta S. (C) 2000 Elsevier Science B.V. All rights reserved.