Spin- and phase transition in the spin crossover complex [Fe(Ptz)6](BF4)2 studied by nuclear inelastic scattering of synchrotron radiation and by DFT calculations

Nuclear inelastic scattering (NIS) spectra of [Fe(PtZ)(6)](BF4)(2) (PtZ = 1-n-propyl-tetrazole) have been measured for five phases differing in spin state and crystallographic structure. Different spectral patterns have been found for the low-spin and high-spin phases and are described in terms of normal coordinate analysis of the complex molecule. For both low-spin and high-spin phases the conversion from ordered to disordered phase results in splitting of the observed NIS bands. Packing becomes visible in the NIS spectra via coupling of the Fe-N stretching vibrations with those of the terminal n-propyl groups. The DFT-based normal coordinate analysis also reveals the character of Raman markers. (c) 2006 Elsevier B.V. All rights reserved.