Published online by Cambridge University Press: 10 February 2011
The electronic and vibrational spectroscopy of one family of metal germanium sulfide open-framework materials, designated Cat2FeGe4S10 (Cat = (CH 3)4N, Cs), along with their precursor Cat4Ge4S10 germanium sulfide clusters have been studied. Ultraviolet-visible and midinfrared reflectance spectroscopy has been used to study the electronic states. The reflectance spectroscopy of the frameworks is dominated by the d-d transitions of the Fe(II) in a S4 symmetry site. The vibrational spectroscopy has been analyzed by Fourier transform Raman. The frameworks are weakly vibrationally coupled. Their spectra contain vibrational modes that are nearly identical in frequency to those of the isolated cluster. There is a fortuitous window in the cluster vibrations in which framework modes of the Fe(II) center can be observed. In addition computational methods have been used to model the experimental results.