Heptacoordinated Molybdenum(VI) Complexes of Phenylenediamine Bis(phenolate): A Stable Molybdenum Amidophenoxide Radical

The syntheses, crystallographic structures, magnetic properties, and theoretical studies of two heptacoordinated molybdenum complexes with N,N'-bis(3,5-di-tert-butyl-2-hydroxyphenyl)-1,2-phenylenediamine (H4N2O2) are reported. A formally molybdenum(VI) complex [Mo(N2O2)Cl-2(dmf)] (1) was synthesized by the reaction between [MoO2Cl2(dmf)(2)] and H4N2O2, whereas the other molybdenum(VI) complex [Mo(N2O2)(HN2O2)] (2) was formed when [MoO2(acac)(2)] was used as a molybdenum source. Both complexes represent a rare case of the Mo-VI ion without any multiply bonded terminal ligands. In addition, molecular structures, magnetic measurements, ESR spectroscopy, and density functional theory calculations indicate that complex 2 is the first stable molybdenum(VI) amidophenoxide radical.