Département de chimie moléculaire

A systematic series of high-spin mononuclear Mn(II), Mn(III), and Mn(IV) complexes was studied by Mn K$\beta$ x-ray emission spectroscopy (XES). The factors contributing to the K$\beta$ main line and the valence to core region are discussed. The K$\beta$ main lines are dominated by 3p-3d exchange correlation (spin state) effects, shifting to lower energy upon oxidn. of Mn(II) to Mn(III) due to the decrease in spin state from S = 5/2 to S = 2, whereas the valence to core region shows greater sensitivity to the chem. environment surrounding the Mn center. A d. functional theory (DFT) approach was used to calc. the valence to core spectra and assess the contributions to the energies and intensities. The valence spectra are dominated by Mn np to 1s elec. dipole-allowed transitions and are particularly sensitive to spin state and ligand identity (reflected primarily in the transition energies) as well as oxidn. state and metal-ligand bond lengths (reflected primarily in the transition intensities). The ability to use these methods to distinguish different ligand contributions within a heteroleptic coordination sphere is highlighted. The similarities and differences between the current Mn XES study and previous studies of Fe XES studies are discussed. These findings serve as an important calibration for future applications to Mn active sites in biol. and chem. catalysis. [on SciFinder(R)]