Modeling the peroxide/superoxide continuum in 1:1 side-on adducts of O2 with Cu.
The character of singlet (C(3)N(2)H(5))CuO(2) ranges smoothly between copper(III) peroxide and copper(II) superoxide with variation of the electronic character of the supporting beta-diketiminate ligand. Over the range of the variation, multireference second-order perturbation theory predicts the (1)A(1) singlet state always to be lower in energy than the lowest triplet state ((3)B(1)). The multideterminantal character of the biradical-like superoxide mesomer causes density functional theory sometimes to fail badly in predicting the relative energies of these same states, although its predictions of other properties, such as geometry, are of good quality.
Gherman
Benjamin F
BF
Department of Chemistry and Supercomputer Institute, University of Minnesota, 207 Pleasant Street SE, Minneapolis, MN 55455, USA.
Cramer
Christopher J
CJ