Journal article
Sulfur K-edge X-ray absorption spectroscopy and time-dependent density functional theory of arsenic dithiocarbamates
Dalton transactions : an international journal of inorganic chemistry, Vol.43(24), pp.9189-9201
06/28/2014
DOI: 10.1039/c4dt00078a
PMID: 24811926
Abstract
S K-edge X-ray absorption spectroscopy (XAS) and time-dependent density functional theory (TDDFT) calculations were performed on a series of As[S2CNR2]3 complexes, where R2 = Et2, (CH2)5 and Ph2, to determine how dithiocarbamate substituents attached to N affect As[S2CNR2]3 electronic structure. Complimentary [PPh4][S2CNR2] salts were also studied to compare dithiocarbamate bonding in the absence of As. The XAS results indicate that changing the orientation of the alkyl substituents from trans to cis (R2 = Et2vs. (CH2)5) yields subtle variations whereas differences associated with a change from alkyl to aryl are much more pronounced. For example, despite the differences in As 4p mixing, the first features in the S K-edge XAS spectra of [PPh4][S2CNPh2] and As[S2CNPh2]3 were both shifted by 0.3 eV compared to their alkyl-substituted derivatives. DFT calculations revealed that the unique shift observed for [PPh4][S2CNPh2] is due to phenyl-induced splitting of the π* orbitals delocalized over N, C and S. A similar phenomenon accounts for the shift observed for As[S2CNPh2]3, but the presence of two unique S environments (As-S and As···S) prevented reliable analysis of As-S covalency from the XAS data. In the absence of experimental values, DFT calculations revealed a decrease in As-S orbital mixing in As[S2CNPh2]3 that stems from a redistribution of electron density to S atoms participating in weaker As···S interactions. Simulated spectra obtained from TDDFT calculations reproduce the experimental differences in the S K-edge XAS data, which suggests that the theory is accurately modeling the experimental differences in As-S orbital mixing. The results highlight how S K-edge XAS and DFT can be used cooperatively to understand the electronic structure of low symmetry coordination complexes containing S atoms in different chemical environments.
Details
- Title: Subtitle
- Sulfur K-edge X-ray absorption spectroscopy and time-dependent density functional theory of arsenic dithiocarbamates
- Creators
- Courtney M Donahue - The George Washington University, Department of Chemistry, 725 21st St, NW, Washington, DC 20052, USA. srdaly@gwu.eduJuan S Lezama PachecoJason M KeithScott R Daly
- Resource Type
- Journal article
- Publication Details
- Dalton transactions : an international journal of inorganic chemistry, Vol.43(24), pp.9189-9201
- Publisher
- England
- DOI
- 10.1039/c4dt00078a
- PMID
- 24811926
- ISSN
- 1477-9226
- eISSN
- 1477-9234
- Language
- English
- Date published
- 06/28/2014
- Academic Unit
- Chemistry
- Record Identifier
- 9983985944902771
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