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X-ray spectroscopy

The electronic structure of binuclear transition metal complexes with disulfide bridged ligands studied by X-ray spectroscopy

Speakers

  • Prof. Lev MAZALOV

Primary authors

Content

Transition metal chalcogenides (TMC) are interesting and practically important classes of inorganic substances. TMC compounds are of great interest due to their chemical, electrophysical, magnetic and optical properties. From a fundamental point of view, TMC are convenient model systems for investigating new physical phenomena and the physicochemical properties inherent in metal cluster compounds and systems with reduced dimensionality.

An important feature of the trichalcogenides (MX3), as well as chain structures [MnX4(n-1)] of IV-VII group transition metal thiocomplexes is the dichalcogenide group X2 (where X = S, Se, Te). Discrete binuclear niobium chalcogenide complexes are convenient model structures for studying the nature of the electronic interaction between the dichalcogenide group (X2) and transition metal atoms in the case of 1D/2D TMC materials. A typical structural fragment of this compounds is the binuclear cluster {Nb2(μ-S2)2-}4+, containing the disulfide group (S2) as bridging ligand. Detailed XES, XAS, XPS and quantum chemical study of the electronic structure of binuclear complexes [Nb2S4(acac)4], K4[Nb2S4(ox)4], TBA4[Nb2S4(SCN)4], Nb2S4Br4 was carried out. SKβ, NbLβ2,15 X-ray emission spectra (XES) were obtained on the X-ray spectrometer "Stearat". NbM2,3, SL2,3, OK, CK and NK X-ray absorption spectra were obtained at the RGBL beamline at BESSY II. Nb3d, S2p, O1s, C1s, N1s X-ray photoelectron spectra were obtained on the spectrometer SPECS (Germany).

Based on the X-ray spectra and quantum chemical calculations, the following data were obtained: 1) HOMO and LUMO energy position and partial molecular orbital compositions in the complexes under study; 2) the electron density distribution in the studied complexes and the atom charges in binuclear clusters {Nb2(μ-S2)2-}4+; 3) the character of molecular orbitals (bonding, anti-bonding).

The reported study was funded by RFBR according to the research project № 18-03-01061 A. The Siberian Branch of the Russian Academy of Sciences (SB RAS) Siberian Supercomputer Center is gratefully acknowledged for providing supercomputer facilities.