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This research elucidates the effects of structural modulations on electroluminescent Au(I) complexes, shedding light on factors governing radiative and nonradiative processes. A series of Au(I) complexes, fortified with ortho‐substituents in carbene and amido ligands, are subjected to rigorous structural, photophysical, and quantum chemical investigations, which unveil distinct structural and electronic effects exerted by the ligands. The investigations reveal that nonradiative processes are governed primarily by the energy‐gap law. Radiative processes are observed to have a weak correlation with the mutual interactions of the molecular orbitals of carbene and amido ligands. Rather, it is discovered that an accumulation of the negative charge in the Au 5d orbital in the excited state decelerates radiative processes. The effectiveness of these findings is substantiated through the larger external quantum efficiency of electroluminescence devices employing the Au(I) complex, in comparison to those based on the archetypical Au(I) complex and the organic thermally activated delayed fluorescent molecule. These compelling revelations underscore the untapped potential of Au(I) complexes in the advancement of electroluminescence technology and advocate for continued investigations into the intriguing domain of ligand structural control. [ABSTRACT FROM AUTHOR]

Oxygen-containing mononuclear iron species--iron(m)-peroxo, iron(III)--hydroperoxo and iron(IV)--oxo--are key intermediates in the catalytic activation of dioxygen by iron-containing metalloenzymes (1-7). It has been difficult to generate synthetic analogues of these three active iron-oxygen species in identical host complexes, which is necessary to elucidate changes to the structure of the iron centre during catalysis and the factors that control their chemical reactivities with substrates. Here we report the high-resolution crystal structure of a mononuclear non-haem side-on iron(III)-peroxo complex, [[Fe(III)(TMC)(OO)].sup.+]. We also report a series of chemical reactions in which this iron(III)-peroxo complex is cleanly converted to the iron(III)-hydroperoxo complex, [[Fe(III)(TMC)(OOH)].sup.2+], via a short-lived intermediate on protonation. This iron(III)-hydroperoxo complex then cleanly converts to the ferryl complex, [[Fe(IV)(TMC)(O)].sup.2+], via homolytic O-O bond cleavage of the iron(III)-hydroperoxo species. All three of these iron species--the three most biologically relevant iron-oxygen intermediates--have been spectroscopically characterized; we note that they have been obtained using a simple macrocyclic ligand. We have performed relative reactivity studies on these three iron species which reveal that the iron(III)-hydroperoxo complex is the most reactive of the three in the deformylation of aldehydes and that it has a similar reactivity to the iron(IV)-oxo complex in C-H bond activation of alkylaromatics. These reactivity results demonstrate that iron(III)-hydroperoxo species are viable oxidants in both nucleophilic and electrophilic reactions by iron-containing enzymes., TMC (1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane) is a macrocyclic ligand of remarkable versatility in the field of biomimetic chemistry of dioxygen activation by metal complexes. A variety of metal complexes of superoxo, peroxo and [...]

We present a theoretical study on the aliphatic C─H bond activation of cyclohexadiene (CHD) by a mononuclear manganese(III) iodosylbenzene complex [MnIII(TBDAP)(OIPh)(OH)]2+ (1). The results suggest that the first step is overall characterized as hydride transfer. However, at the more fundamental level, this step consists of a hydrogen atom transfer and a subsequent electron transfer. [ABSTRACT FROM AUTHOR]

The dioxygenation of nitriles by [CoIII(TBDAP)(O2)]+ (TBDAP = N,N-di-tert-butyl-2,11-diaza[3.3](2,6)-pyridinophane) is investigated using DFT-calculations. The mechanism proposed previously based on experimental observations, which invoked an outer-sphere cycloaddition, was found to be unreasonable. Instead, calculations suggest that an inner-sphere mechanism involving the cleavage of one of the Co–O bonds assisted by substrate uptake is much more likely. The reactively competent species is a triplet consisting of a Co(II)-superoxo functionality, which can undergo O–C bond formation and O–O bond cleavage traversing low energy transition states. The role of the structurally rigid TBDAP ligand is to prevent the participation of the pyridyl ligand in the delocalization of the unpaired electron density. [ABSTRACT FROM AUTHOR]