Creator: Zhou, Xin; Hrovat, David A. & Borden, Weston T., 1943-
Description: This article discusses ground states. Abstract: B3LYP, CCSD(T), and CASPT2 calculations with the 6-311+G(2df) basis set have been performed on the radical anion and radical cation of cyclobutanetetraone (1). The very similar energies computed for the 2B1g and 2A2u states of both 1·+ and 1·- indicate that the singly occupied b1g and a2u MOs in these two states of the radical cation and anion have nearly the same energies, thus supporting the previously made prediction that neutral 1 has a 3B2u ground state. Reaction of squaric acid with O.(-), followed by negative ion photoelectron spectroscopy (NIPES) on the 1.(-) thus formed, is proposed as an experimental test of the startling prediction that tetraketone (1), a molecule that would be expected to be a closed-shell singlet, actually has a triplet ground state.
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