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Title: A Solid-State 95Mo NMR and Computational Investigation of Dodecahedral and Square Antiprismatic Octacyanomolybdate(IV) Anions: Is the Point-Charge Approximation an Accurate Probe of Local Symmetry?

Abstract

Solid-state 95Mo NMR spectroscopy is shown to be an efficient and effective tool for analyzing the diamagnetic octacyanomolybdate(IV) anions, Mo(CN)8 4-, of approximate dodecahedral, D2d, and square antiprismatic, D4d, symmetry. The sensitivity of the Mo magnetic shielding (?) and electric field gradient (EFG) tensors to small changes in the local structure of these anions allows the approximate D2d and D4d Mo(CN)8 4- anions to be readily distinguished. The use of high applied magnetic fields, 11.75, 17.63 and 21.1 T, amplifies the overall sensitivity of the NMR experiment and enables more accurate characterization of the Mo ? and EFG tensors. Although the magnitudes of the Mo ? and EFG interactions are comparable for the D2d and D4d Mo(CN)8 4- anions, the relative values and orientations of the principal components of the Mo ? and EFG tensors give rise to 95Mo NMR line shapes that are significantly different at the fields utilized here. Quantum chemical calculations of the Mo ? and EFG tensors, using zeroth-order regular approximation density functional theory (ZORA DFT) and restricted Hartree-Fock (RHF) methods, have also been carried out and are in good agreement with experiment. The most significant and surprising result from the DFT and RHF calculations ismore » a significant EFG at Mo for an isolated Mo(CN)8 4- anion possessing an ideal square antiprismatic structure; this is contrary to the point-charge approximation, PCA, which predicts a zero EFG at Mo for this structure.« less

Authors:
;
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL)
Sponsoring Org.:
USDOE
OSTI Identifier:
889057
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article
Journal Name:
Journal of the American Chemical Society
Additional Journal Information:
Journal Volume: 128; Journal Issue: 24; Journal ID: ISSN 0002-7863
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; MOLYBDATES; CYANIDES; NUCLEAR MAGNETIC RESONANCE; MICROSTRUCTURE; DENSITY FUNCTIONAL METHOD; HARTREE-FOCK METHOD; POINT CHARGE; SENSITIVITY; SYMMETRY; Environmental Molecular Sciences Laboratory

Citation Formats

Forgeron, Michelle A, and Wasylishen, Roderick E. A Solid-State 95Mo NMR and Computational Investigation of Dodecahedral and Square Antiprismatic Octacyanomolybdate(IV) Anions: Is the Point-Charge Approximation an Accurate Probe of Local Symmetry?. United States: N. p., 2006. Web. doi:10.1021/ja060124x.
Forgeron, Michelle A, & Wasylishen, Roderick E. A Solid-State 95Mo NMR and Computational Investigation of Dodecahedral and Square Antiprismatic Octacyanomolybdate(IV) Anions: Is the Point-Charge Approximation an Accurate Probe of Local Symmetry?. United States. https://doi.org/10.1021/ja060124x
Forgeron, Michelle A, and Wasylishen, Roderick E. 2006. "A Solid-State 95Mo NMR and Computational Investigation of Dodecahedral and Square Antiprismatic Octacyanomolybdate(IV) Anions: Is the Point-Charge Approximation an Accurate Probe of Local Symmetry?". United States. https://doi.org/10.1021/ja060124x.
@article{osti_889057,
title = {A Solid-State 95Mo NMR and Computational Investigation of Dodecahedral and Square Antiprismatic Octacyanomolybdate(IV) Anions: Is the Point-Charge Approximation an Accurate Probe of Local Symmetry?},
author = {Forgeron, Michelle A and Wasylishen, Roderick E},
abstractNote = {Solid-state 95Mo NMR spectroscopy is shown to be an efficient and effective tool for analyzing the diamagnetic octacyanomolybdate(IV) anions, Mo(CN)8 4-, of approximate dodecahedral, D2d, and square antiprismatic, D4d, symmetry. The sensitivity of the Mo magnetic shielding (?) and electric field gradient (EFG) tensors to small changes in the local structure of these anions allows the approximate D2d and D4d Mo(CN)8 4- anions to be readily distinguished. The use of high applied magnetic fields, 11.75, 17.63 and 21.1 T, amplifies the overall sensitivity of the NMR experiment and enables more accurate characterization of the Mo ? and EFG tensors. Although the magnitudes of the Mo ? and EFG interactions are comparable for the D2d and D4d Mo(CN)8 4- anions, the relative values and orientations of the principal components of the Mo ? and EFG tensors give rise to 95Mo NMR line shapes that are significantly different at the fields utilized here. Quantum chemical calculations of the Mo ? and EFG tensors, using zeroth-order regular approximation density functional theory (ZORA DFT) and restricted Hartree-Fock (RHF) methods, have also been carried out and are in good agreement with experiment. The most significant and surprising result from the DFT and RHF calculations is a significant EFG at Mo for an isolated Mo(CN)8 4- anion possessing an ideal square antiprismatic structure; this is contrary to the point-charge approximation, PCA, which predicts a zero EFG at Mo for this structure.},
doi = {10.1021/ja060124x},
url = {https://www.osti.gov/biblio/889057}, journal = {Journal of the American Chemical Society},
issn = {0002-7863},
number = 24,
volume = 128,
place = {United States},
year = {Wed Jun 21 00:00:00 EDT 2006},
month = {Wed Jun 21 00:00:00 EDT 2006}
}