Exchange Interaction in Complex Bis[(1,3-Dithiole-2-Thione-4,5-Dithiolato)-di-(Carbonyl)-Cyclopentadienyl Iron(II)]

The splitting of the quasidegenerate electronic states in dinuclear bis[(1,3-dithiole-2-thione-4,5-dithiolato)-di-(carbonyl)-cyclopentadienyliron (II)] complex with the bridging, S–S coupled, dimerized sulfur-rich dithiolate ligands, [Fe(C5H5)(CO)2(C3S5-C3S5)Fe(C5H5)(CO)2] (I) was found by the means of Mössbauer spectroscopy and by the measurement of the temperature dependence of magnetic susceptibility in a wide temperature range from 2 K to 300 K. The experimental results were confirmed by the calculations of the singlet and triplet states of the complex, as well as of the distribution of spin density within the bounds of the DFT method in the B3LYP/6-31(dp)G basis. In the more stable triplet state, the spin density is significantly delocalized, which is a characteristic of olefindithiolate complexes