  Raman scattering in the spin-crossover system [Fe(pmd)(H2O){Au(CN)2}2]*H2O
reveals a complex three-phase spin-state transition in contrast to earlier
observations in magnetization measurements. We observe different spin state
phases as function of temperature and electromagnetic radiation in the visible
spectral range. There exists a fluctuating spin state phase with an unexpected
wipeout of the low frequency phonon scattering intensity. Furthermore we
observe one phase with reduced symmetry that is attributed to a cooperative
Jahn-Teller effect. Pronounced electron-phonon interaction manifests itself as
a strong Fano-resonance of phonons related to {FeN6} and {FeN4O2} coordination
octahedra. Density functional theory supports this interpretation.
