Thermodynamics of a μ-oxo Dicopper(Ⅱ) Complex for Hydrogen Atom Abstraction

摘要

The mono-μ-hydroxo complex {[Cu(tmpa)]_(2)-(μ-OH)}~(3+) ( 1 ) can undergo reversible deprotonation at −30 °C to yield {[Cu(tmpa)]_(2)-(μ-O)}~(2+) ( 2 ). This species is basic with a p K _(a) of 24.3. 2 is competent for concerted proton–electron transfer from TEMPOH, but is an intrinsically poor hydrogen atom abstractor (BDFE(OH) of 77.2 kcal/mol) based on kinetic and thermodynamic analyses. Nonetheless, DFT calculations experimentally calibrated against 2 reveal that [Cu_(2)O]~(2+) is likely thermodynamically viable in copper-dependent methane monoxygenase enzymes.