Resonance Raman spectroscopy of bis(isomaleonitriledithiolato)nickelate(II) as a probe to the chromophore extension

The resonance Raman spectrum of bis(isomaleonitriledithiolato)nickelate(II) was investigated in order to assess the extent of the electronic delocalization within the chromophore. Previous results for the isomeric species bis(maleonitriledithiolato)nickelate(II) indicated an extensive delocalization involving the Ni—S, C=C and C≡N bonds. The present results conclusively indicate that in the case of [Ni(imnt)]2− the delocalization is much more restricted, which is in line with a previous suggestion concerning the marked difference in the two species concerning the stability towards oxidation. The resonance Raman results show a very pronounced enhancement of the v(Ni—S) and δ(ring) modes via the Albrech's A term, which is supported by the simulations undertaken using the transform method and the time-dependent approach.