RESONANCE RAMAN-SPECTROSCOPY OF BIS(ISOMALEONITRILEDITHIOLATO)NICKELATE(II) AS A PROBE TO THE CHROMOPHORE EXTENSION

The resonance Raman spectrum of bis(isomaleonitriledithiolato)nickelat e(II) was investigated in order to assess the extent of the electronic delocalization within the chromophore. Previous results for the isome ric species bis(maleonitriledithiolato)nickelate(II) indicated an exte nsive delocalization involving the Ni-S, C=C and C=N bonds. The presen t results conclusively indicate that in the case of [Ni(imnt)](2-) the delocalization is much more restricted, which is in line with a previ ous suggestion concerning the marked difference in the two species con cerning the stability towards oxidation. The resonance Raman results s how a very pronounced enhancement of the nu(Ni-S) and delta(ring) mode s via the Albrech's A term, which is supported by the simulations unde rtaken using the transform method and the time-dependent approach.