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Title: Determining Relative f and d Orbital Contributions to M–Cl Covalency in MCl 6 2– (M = Ti, Zr, Hf, U) and UOCl 5 Using Cl K-Edge X-ray Absorption Spectroscopy and Time-Dependent Density Functional Theory

Abstract

Chlorine K-edge X-ray absorption spectroscopy (XAS) and ground-state and time-dependent hybrid density functional theory (DFT) were used to probe electronic structure for O{sub h}-MCl{sub 6}{sup 2-}(M = Ti, Zr, Hf, U) and C{sub 4v}-UOCl{sub 5}{sup -}, and to determine the relative contributions of valence 3d, 4d, 5d, 6d, and 5f orbitals in M-Cl bonding. Spectral interpretations were guided by time-dependent DFT calculated transition energies and oscillator strengths, which agree well with the experimental XAS spectra. The data provide new spectroscopic evidence for the involvement of both 5f and 6d orbitals in actinide-ligand bonding in UCl{sub 6}{sup 2-}. For the MCl{sub 6}{sup 2-}, where transitions into d orbitals of t{sub 2g} symmetry are spectroscopically resolved for all four complexes, the experimentally determined Cl 3p character per M-Cl bond increases from 8.3(4)% (TiCl{sub 6}{sup 2-}) to 10.3(5)% (ZrCl{sub 6}{sup 2-}), 12(1)% (HfCl{sub 6}{sup 2-}), and 26 18(1)% (UCl{sub 6}{sup 2-}). Chlorine K-edge XAS spectra of UOCl{sub 5}{sup -} provide additional insights into the transition assignments by 27 lowering the symmetry to C{sub 4v}, where five pre-edge transitions into both 5f and 6d orbitals are observed. For UCl{sub 6}{sup 2-}, the XAS data 28 suggest that orbital mixing associated with the U 5fmore » orbitals is considerably lower than that of the U 6d orbitals. For both UCl{sub 6}{sup 2-}29 and UOCl{sub 5}{sup -}, the ground-state DFT calculations predict a larger 5f contribution to bonding than is determined experimentally. 30 These findings are discussed in the context of conventional theories of covalent bonding for d- and f-block metal complexes.« less

Authors:
; ; ; ; ; ; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
Sponsoring Org.:
USDOE
OSTI Identifier:
1039837
Report Number(s):
PNNL-SA-86363
Journal ID: ISSN 0002-7863; 40074; KP1504010; TRN: US201210%%64
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article
Journal Name:
Journal of the American Chemical Society
Additional Journal Information:
Journal Volume: 134; Journal Issue: 12; Journal ID: ISSN 0002-7863
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ABSORPTION SPECTROSCOPY; BONDING; CHLORINE; COVALENCE; ELECTRONIC STRUCTURE; FUNCTIONALS; OSCILLATOR STRENGTHS; PROBES; SPECTRA; SYMMETRY; VALENCE; Covalency, f-orbitals, spectra, M-Cl bond, time-dependent density functional theory; Environmental Molecular Sciences Laboratory

Citation Formats

Minasian, Stefan G., Keith, Jason M., Batista, Enrique R., Boland, Kevin S., Clark, David L., Conradson, Steven D., Kozimor, Stosh A., Martin, Richard L., Schwarz, Daniel E., Shuh, David K., Wagner, Gregory L., Wilkerson, Marianne P., Wolfsberg, Laura E., and Yang, Ping. Determining Relative f and d Orbital Contributions to M–Cl Covalency in MCl 6 2– (M = Ti, Zr, Hf, U) and UOCl 5 – Using Cl K-Edge X-ray Absorption Spectroscopy and Time-Dependent Density Functional Theory. United States: N. p., 2012. Web. doi:10.1021/ja2105015.
Minasian, Stefan G., Keith, Jason M., Batista, Enrique R., Boland, Kevin S., Clark, David L., Conradson, Steven D., Kozimor, Stosh A., Martin, Richard L., Schwarz, Daniel E., Shuh, David K., Wagner, Gregory L., Wilkerson, Marianne P., Wolfsberg, Laura E., & Yang, Ping. Determining Relative f and d Orbital Contributions to M–Cl Covalency in MCl 6 2– (M = Ti, Zr, Hf, U) and UOCl 5 – Using Cl K-Edge X-ray Absorption Spectroscopy and Time-Dependent Density Functional Theory. United States. doi:10.1021/ja2105015.
Minasian, Stefan G., Keith, Jason M., Batista, Enrique R., Boland, Kevin S., Clark, David L., Conradson, Steven D., Kozimor, Stosh A., Martin, Richard L., Schwarz, Daniel E., Shuh, David K., Wagner, Gregory L., Wilkerson, Marianne P., Wolfsberg, Laura E., and Yang, Ping. Wed . "Determining Relative f and d Orbital Contributions to M–Cl Covalency in MCl 6 2– (M = Ti, Zr, Hf, U) and UOCl 5 – Using Cl K-Edge X-ray Absorption Spectroscopy and Time-Dependent Density Functional Theory". United States. doi:10.1021/ja2105015.
@article{osti_1039837,
title = {Determining Relative f and d Orbital Contributions to M–Cl Covalency in MCl 6 2– (M = Ti, Zr, Hf, U) and UOCl 5 – Using Cl K-Edge X-ray Absorption Spectroscopy and Time-Dependent Density Functional Theory},
author = {Minasian, Stefan G. and Keith, Jason M. and Batista, Enrique R. and Boland, Kevin S. and Clark, David L. and Conradson, Steven D. and Kozimor, Stosh A. and Martin, Richard L. and Schwarz, Daniel E. and Shuh, David K. and Wagner, Gregory L. and Wilkerson, Marianne P. and Wolfsberg, Laura E. and Yang, Ping},
abstractNote = {Chlorine K-edge X-ray absorption spectroscopy (XAS) and ground-state and time-dependent hybrid density functional theory (DFT) were used to probe electronic structure for O{sub h}-MCl{sub 6}{sup 2-}(M = Ti, Zr, Hf, U) and C{sub 4v}-UOCl{sub 5}{sup -}, and to determine the relative contributions of valence 3d, 4d, 5d, 6d, and 5f orbitals in M-Cl bonding. Spectral interpretations were guided by time-dependent DFT calculated transition energies and oscillator strengths, which agree well with the experimental XAS spectra. The data provide new spectroscopic evidence for the involvement of both 5f and 6d orbitals in actinide-ligand bonding in UCl{sub 6}{sup 2-}. For the MCl{sub 6}{sup 2-}, where transitions into d orbitals of t{sub 2g} symmetry are spectroscopically resolved for all four complexes, the experimentally determined Cl 3p character per M-Cl bond increases from 8.3(4)% (TiCl{sub 6}{sup 2-}) to 10.3(5)% (ZrCl{sub 6}{sup 2-}), 12(1)% (HfCl{sub 6}{sup 2-}), and 26 18(1)% (UCl{sub 6}{sup 2-}). Chlorine K-edge XAS spectra of UOCl{sub 5}{sup -} provide additional insights into the transition assignments by 27 lowering the symmetry to C{sub 4v}, where five pre-edge transitions into both 5f and 6d orbitals are observed. For UCl{sub 6}{sup 2-}, the XAS data 28 suggest that orbital mixing associated with the U 5f orbitals is considerably lower than that of the U 6d orbitals. For both UCl{sub 6}{sup 2-}29 and UOCl{sub 5}{sup -}, the ground-state DFT calculations predict a larger 5f contribution to bonding than is determined experimentally. 30 These findings are discussed in the context of conventional theories of covalent bonding for d- and f-block metal complexes.},
doi = {10.1021/ja2105015},
journal = {Journal of the American Chemical Society},
issn = {0002-7863},
number = 12,
volume = 134,
place = {United States},
year = {2012},
month = {3}
}