X-ray absorption spectroscopy study of the electronic structure and local coordination of 1st row transition metal-promoted Chevrel-phase sulfides. Issue 8 (18th April 2019)

• Record Type: Journal Article
• Authors: Perryman, Joseph T.; Hyler, Forrest P.; Ortiz-Rodríguez, Jessica C.; Mehta, Apurva; Kulkarni, Ambarish R.; Velázquez, Jesús M.
• Is Part Of: Journal of coordination chemistry. Volume 72:Issue 8(2019)
• Page Start: 1322
• Page End: 1335
• Publication Date: 2019-04-18
• Subjects: Chevrel-phase -- X-ray absorption -- DFT -- coordination -- electronic structure; Coordination compounds -- Periodicals; 541.2242
• DOI: 10.1080/00958972.2019.1613532
• Languages: English
• ISSNs: 0095-8972

Abstract

Abstract: The electronic structures of S and Mo as well as the local coordination of Mo are investigated as a function of metal promotion Chevrel-phase (CP) sulfides. We observe the effect of metal promoter-induced electron donation into the stoichiometric range M x Mo6 S8 (M = Fe, Ni, Cu; x = 0–2) through analysis of X-ray absorption near-edge structure regions. We further observe the effect of this promotion on the bonding environment of Mo6 metal centers through extended X-ray absorption fine structure analysis. We monitor expansion and contraction of Mo6 octahedra with and without metal promotion, as has been predicted by Hückel molecular orbital theory. We further observe a marked tunability in the electronic structure of sulfur upon charge transfer between promoting species and Mo6 S8 units. Average Mo6 octahedron Mo–Mo bond contraction from 2.76 Å to as short as 2.69 Å was observed upon incorporation of metal promoters, while intercluster separation displays a pronounced increase for promoter-host lattices compared to un-promoted Mo6 S8 . To corroborate spectroscopically observed phenomena, we performed computational analyses of spin-polarized densities of state for the CP materials investigated herein, where a detectable increase in sulfur-based frontier orbital population is observed in accordance with experimentally validated orbital filling. Graphical abstract: