A Structural Model for the High-Valent Intermediate Q of Methane Monooxygenase from Broken-Symmetry Density Functional and Electrostatics Calculations

A combined broken-symmetry density functional and electrostatics approach has been used to construct a model for the high-valent diiron intermediate Q of methane monooxygenase. The presence of high-spin or intermediate spin iron centers gives rise to two structurally distinct spin-coupled states of the cluster for which calculated geometries, net spin populations, Heisenberg J values, Mössbauer isomer shifts, and quadrupole splittings are compared and contrasted with the available spectroscopic data.