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Dioxygen Reactivity of a Copper(I) Complex with a N3S Thioether Chelate; Peroxo−Dicopper(II) Formation Including Sulfur-Ligation

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journal contribution
posted on 11.12.2006, 00:00 by Lanying Q. Hatcher, Dong-Heon Lee, Michael A. Vance, Ashley E. Milligan, Ritimukta Sarangi, Keith O. Hodgson, Britt Hedman, Edward I. Solomon, Kenneth D. Karlin
Employing a tetradentate N3S(thioether) ligand, LN3S, dioxygen reactivity of a copper(I) complex, [(LN3S)CuI]+ (1) was examined. In CH2Cl2, acetone (at −80 °C), or 2-methyltetrahydrofuran (at −128 °C), 1 reacts with O2 producing the end-on bound peroxodicopper(II) complex [{(LN3S)CuII}2(μ-1,2-O22-)]2+ (2), the first reported copper−dioxygen adduct with sulfur (thioether) ligation. Its absorption spectrum contains an additional low-energy feature (but not a Cu−S CT band) compared to the previously well-characterized N4 ligand complex, [{(TMPA)CuII}2(μ-1,2-O22-)]2+ (3) (TMPA = tris(2-pyridylmethyl)amine). Resonance Raman spectroscopy confirms the peroxo formulation {ν(O-O) = 817 cm-1 (16-18O2 Δ = 46 cm-1) and ν(Cu-O) = 545 cm-1 (16-18O2 Δ = 26 cm-1), in close analogy to that known for 3(O-O) = 827 cm-1 and ν(Cu-O) = 561 cm-1}. Direct evidence for thioether ligation comes from EXAFS spectroscopy {Cu K-edge; Cu−S = 2.4 Å}