Inelastic neutron scattering study of low frequency motions in [Co(C 5H 5) 2+] and [Cr(C 6 H 62+] intercalated in the MnPS 3 layered compound

Abstract

The incoherent inelastic neutron scattering (INS) spectra of Mn 0.84PS 3[Co(C 5H 5) 2] 0.32 and Mn 0.86 PS 3[Cr(C 6H 6) 2] 0.28 compounds at 10 K have been investigated within the frequency ranges 0–80 cm −1 ( E 0 = 12.5 meV) and 0–360 cm −1 ( E 0 = 50 meV). Also, infrared and Raman spectra (0–400 cm −1 of Cr(C 6H 6) 2I at various temperatures have been obtained for the first time. From a comparison of far infrared, low frequency Raman and INS results, we propose an assignment for the internal torsion and for the librational motions in the intercalated organometallic cations. An estimate of the potential barrier height against the torsion and the R′ z whole-body rotation is derived; these values are compared with those calculated for the corresponding iodide salts. We conclude that a significant decrease of the intermolecular forces acting on the rings is taking place within the interlamellar space.