Polarized specular reflectance spectra of Fe(beta-dtpy)(2)center dot 4THF:A D-2h model of porphyrins

Transition metal complexes of beta-dtpy (1,2,6,7-tetracyano-3,5-dihydro-3,5 -diiminopyrrolizinide) are spectrally similar to metallophthalocyanines (de rivatives of porphyrin) but with the advantage of being D-2h instead of D-4 h so that many degenerate electronic transitions are identifiable separatel y. We have prepared and characterized Fe(beta-dtpy)(2). 4THF, whose crystal structure allows three spectral polarizations to be measured. We have assi gned the visible and ultraviolet transitions that correspond to the Q and S oret regions of porphyrinic complexes; these assignments differ markedly fr om the traditional "four-orbital" model. The secondary Q peak (R) is a sepa rate electronic transition rather than a vibronic component, and the Soret transition has been reassigned.