Speaker
Description
Tasks arising with the growing need for alternative renewable energy sources and environmentally pure catalytic technologies stimulate the search for new functional materials. At present, growing interest is in compounds containing chalcogenide and dichalcogenide groups, which may perform as active catalytic centers. In this regard, binuclear and trinuclear transition metal clusters modified with various terminal ligands have great prospects as catalysts or precursors with higher catalytic activity, and could be considered convenient structural models of active centers of industrial catalysts. The coordination of terminal ligands of various nature affects the electronic structure of clusters, which could improve functional properties such as nonlinear optical properties, reactivity, and other physicochemical properties.
An important issue in obtaining new functional materials is the characterization of their atomic and electronic structures. Thus, the electrocatalytic activity of materials based on dichalcogenide molybdenum clusters or MoS2 nanoparticles with different morphologies is associated with a large number of disulfide groups in the catalyst structure. X-ray spectroscopy provides information about both the atomic and the electronic structure of the studied compounds.
In the present work, the electronic structure of a series of binuclear and trinuclear transition metal clusters with disulfide and sulfide ligands was studied by X-ray spectroscopy methods. The S K-edge, S L2,3-edge XANES spectra, and S Kβ, M Lβ X-ray emission spectra of complexes with various cluster core ({M2S4}, {M3S7}, {M3S4}, M = Mo, Nb, V, W) were studied. Based on quantum chemical calculations, the X-ray absorption and X-ray emission spectra of sulfur atoms were interpreted, providing information on the energy position and partial atomic composition of the HOMOs and LUMOs, and the electron density distribution in the clusters under study. Based on the obtained experimental and theoretical data, the effect of external sphere ligands on the nature of the electronic interactions of cluster core, the electronic structure of bridge sulfide and disulfide ligands was studied. The electronic structures of transition metal disulfides and disulfide clusters were compared.
This work was supported by RFBR grant № 18-03-01061a.
The work was done at the shared research center SSTRC on the basis of the Novosibirsk FEL/VEPP-4 - VEPP-2000 complex at BINP SB RAS, using equipment supported by project RFMEFI62119X0022.
