Matrix isolation infrared study of the interaction of dioxygen with chromium(II)tetraphenylporphyrin

Abstract The infrared spectra of Cr(II)(TPP) (TPP is meso-tetraphenylporphyrinato dianion) and its adduct with molecular oxygen have been recorded in argon matrices at 10 K, as well as in thin sublimated films. Formation of the Cr(TPP)(O2) adduct have been confirmed using 16O2 and 18O2. The ν(O2) stretching bands are located at 1146 and 1082 cm−1, respectively. These and literature data together with the results of our DFT calculations, are consistent with the end-on dioxygen binding mode in the Cr(III)(TPP)(O2–) superoxo complex.