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Spectroscopic and Computational Studies of an End-on Bound Superoxo-Cu(II) Complex: Geometric and Electronic Factors That Determine the Ground State

2010; American Chemical Society; Volume: 49; Issue: 20 Linguagem: Inglês

10.1021/ic101138u

1520-510X

Julia S. Woertink, Li Tian, Debabrata Maiti, Heather R. Lucas, Richard A. Himes, Kenneth D. Karlin, Frank Neese, Christian Würtele, Max C. Holthausen, Eckhard Bill, Jörg Sundermeyer, Siegfried Schindler, Edward I. Solomon,

Lanthanide and Transition Metal Complexes

A variety of techniques including absorption, magnetic circular dichroism (MCD), variable-temperature, variable-field MCD (VTVH-MCD), and resonance Raman (rR) spectroscopies are combined with density functional theory (DFT) calculations to elucidate the electronic structure of the end-on (η1) bound superoxo-Cu(II) complex [TMG3trenCuO2]+ (where TMG3tren is 1,1,1-tris[2-[N2-(1,1,3,3-tetramethylguanidino)]ethyl]amine). The spectral features of [TMG3trenCuO2]+ are assigned, including the first definitive assignment of a superoxo intraligand transition in a metal-superoxo complex, and a detailed description of end-on superoxo-Cu(II) bonding is developed. The lack of overlap between the two magnetic orbitals of [TMG3trenCuO2]+ eliminates antiferromagnetic coupling between the copper(II) and the superoxide, while the significant superoxo π*σ character of the copper dz2 orbital leads to its ferromagnetically coupled, triplet, ground state.