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Title: An Investigation of Lanthanum Coordination Compounds by Using Solid-State139La NMR Spectroscopy and Relativistic Density Functional Theory

Authors:
; ; ;
Publication Date:
Research Org.:
Environmental Molecular Sciences Laboratory (EMSL)
Sponsoring Org.:
USDOE Office of Science (SC), Biological and Environmental Research (BER)
OSTI Identifier:
1152253
Resource Type:
Journal Article
Resource Relation:
Journal Name: Chemistry - A European Journal; Journal Volume: 12; Journal Issue: 1
Country of Publication:
United States
Language:
English

Citation Formats

Mathew J.,Willans, Kirk W.,Feindel, Kristopher J.,Ooms, and Roderick E.,Wasylishen. An Investigation of Lanthanum Coordination Compounds by Using Solid-State139La NMR Spectroscopy and Relativistic Density Functional Theory. United States: N. p., 2006. Web. doi:10.1002/chem.200500778.
Mathew J.,Willans, Kirk W.,Feindel, Kristopher J.,Ooms, & Roderick E.,Wasylishen. An Investigation of Lanthanum Coordination Compounds by Using Solid-State139La NMR Spectroscopy and Relativistic Density Functional Theory. United States. doi:10.1002/chem.200500778.
Mathew J.,Willans, Kirk W.,Feindel, Kristopher J.,Ooms, and Roderick E.,Wasylishen. Sun . "An Investigation of Lanthanum Coordination Compounds by Using Solid-State139La NMR Spectroscopy and Relativistic Density Functional Theory". United States. doi:10.1002/chem.200500778.
@article{osti_1152253,
title = {An Investigation of Lanthanum Coordination Compounds by Using Solid-State139La NMR Spectroscopy and Relativistic Density Functional Theory},
author = {Mathew J.,Willans and Kirk W.,Feindel and Kristopher J.,Ooms and Roderick E.,Wasylishen},
abstractNote = {},
doi = {10.1002/chem.200500778},
journal = {Chemistry - A European Journal},
number = 1,
volume = 12,
place = {United States},
year = {Sun Jan 01 00:00:00 EST 2006},
month = {Sun Jan 01 00:00:00 EST 2006}
}
  • Lanthanum-139 NMR spectra of stationary samples of several solid LaIII coordination compounds have been obtained at applied magnetic fields of 11.75 and 17.60 T. The breadth and shape of the 139La NMR spectra of the central transition are dominated by the interaction between the 139La nuclear quadrupole moment and the electric field gradient (EFG) at that nucleus; however, the influence of chemical-shift anisotropy on the NMR spectra is non-negligible for the majority of the compounds investigated. Analysis of the experimental NMR spectra reveals that the 139La quadrupolar coupling constants (CQ) range from 10.0 to 35.6 MHz, the spans of themore » chemical-shift tensor (W) range from 50 to 260 ppm, and the isotropic chemical shifts (diso) range from -80 to 178 ppm. In general, there is a correlation between the magnitudes of CQ and W, and diso is shown to depend on the La coordination number. Magnetic shielding tensors, calculated by using relativistic zeroth-order regular approximation density functional theory (ZORA-DFT) and incorporating scalar only or scalar plus spin-orbit relativistic effects, qualitatively reproduce the experimental chemical-shift tensors. In general, the inclusion of spin-orbit coupling yields results that are in better agreement with those from the experiment. The magnetic-shielding calculations and experimentally determined Euler angles can be used to predict the orientation of the chemical-shift and EFG tensors in the molecular frame. This study demonstrates that solid state 139La NMR spectroscopy is a useful characterization method and can provide insight into the molecular structure of lanthanum coordination compounds.« less
  • The reaction of Re{sub 2}O{sub 7} with XeF{sub 6} in anhydrous HF provides a convenient route to high-purity ReO{sub 2}F{sub 3}. The fluoride acceptor and Lewis base properties of ReO{sub 2}F{sub 3} have been investigated leading to the formation of [M][ReO{sub 2}F{sub 4}] [M = Li, Na, Cs, N(CH{sub 3}){sub 4}], [K][Re{sub 2}O{sub 4}F{sub 7}], [K][Re{sub 2}O{sub 4}F{sub 7}]{center_dot}2ReO{sub 2}F{sub 3}, [Cs][Re{sub 3}O{sub 6}F{sub 10}], and ReO{sub 2}F{sub 3}(CH{sub 3}CN). The ReO{sub 2}F{sub 4}{sup {minus}}, Re{sub 2}O{sub 4}F{sub 7}{sup {minus}}, and Re{sub 3}O{sub 6}F{sub 10{sup {minus}} anions and the ReO{sub 2}F{sub 3}(CH{sub 3}CN) adduct have been characterized in the solidmore » state by Raman spectroscopy, and the structures [Li][ReO{sub 2}F{sub 4}], [K][Re{sub 2}O{sub 4}F{sub 7}], [K][Re{sub 2}O{sub 4}F{sub 7}]{center_dot}2ReO{sub 2}F{approximately}3}, [Cs][Re{sub 3}O{sub 6}F{sub 10}], and ReO{sub 3}F(CH{sub 3}CN){sub 2}{center_dot}CH{sub 3}CN have been determined by X-ray crystallography. The structure of ReO{sub 2}F{sub 4}{sup {minus}} consists of a cis-dioxo arrangement of Re-O double bonds in which the Re-F bonds trans to the oxygen atoms are significantly lengthened as a result of the trans influence of the oxygens. The Re{sub 2}O{sub 4}F{sub 7}{sup {minus}} and Re{sub 3}O{sub 6}F{sub 10}{sup {minus}} anions and polymeric ReO{sub 2}F{sub 3} are open chains containing fluorine-bridged ReO{sub 2}F{sub 4} units in which each pair of Re-O bonds are cis to each other and the fluorine bridges are trans to oxygens. The trans influence of the oxygens is manifested by elongated terminal Re-F bonds trans to Re-O bonds as in ReO{sub 2}F{sub 4}{sup {minus}} and by the occurrence of both fluorine bridges trans to Re-O bonds. Fluorine-19 NMR spectra show that ReO{sub 2}F{sub 4}{sup {minus}}, Re{sub 2}O{sub 4}F{sub 7}{sup {minus}}, and ReO{sub 2}F{sub 3}(CH{sub 3}CN) have cis-dioxo arrangements in CH{sub 3}CN solution. Density functional theory calculations at the local and nonlocal levels confirm that the cis-dioxo isomers of ReO{sub 2}F{sub 4}{sup {minus}} and ReO{sub 2}F{sub 3}(CH{sub 3}CN), where CH{sub 3}CN is bonded trans to an oxygen, are the energy-minimized structures. The adduct ReO{sub 3}F(CH{sub 3}CN){sub 2}{center_dot}CH{sub 3}CN was obtained by hydrolysis of ReO{sub 2}F{sub 3}(CH{sub 3}CN), and was shown by X-ray crystallography to have a facial arrangement of oxygen atoms on rhenium.« less
  • A portion of the following research was conducted at EMSL. The metal NMR parameters of the complexes [(NC) 5Pt–Tl(CN) n] n- (n = 0–3, I–IV) and [(NC) 5Pt–Tl–Pt(CN) 5] 3- (V), as well as [fPt(NO 3)(NH 3) 2L 2gTl(NO 3) 2(MeOH)] (VI) and [fPt(NO 3)(NH 3) 2L 2g 2Tl] + (VII) with L =NHCOtBu,were computationally investigated by relativistic density functional theory. Complexes I–V were previously studied by us. We briefly review the main findings here. Their spin–spin coupling constants are analyzed in terms ofmolecular orbital and fragment orbital contributions which demonstrate the various influences of the solvent and of themore » ligands on the extraordinarily large metal–metal coupling constants. Complexes VI and VII and various model systems were investigated in more detail. It is shown that the same computational model which performs best for I–V yields too large metal–metal coupling constants for VI and VII. The analysis shows that this is likely to be attributable to a strong sensitivity of the coupling constants to the rather small Pt 6s contributions in the occupied metal–metal s-bonding orbitals. Bulk solvent effects on the metal–metal couplings are sizeable and should be considered in the computational model. Both calculated and experimental Pt–Tl coupling constants for VI and VII are substantially larger than those for I–V, thereby representing the largest heteronuclear coupling constants known so far experimentally. Metal chemical shifts for VI and VII were also investigated. The computational results indicate that the choice of the Pt reference is rather problematic. Tl chemical shifts agree much better with experimental data.« less