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Title: A solid-state 55Mn NMR spectroscopy and DFT investigation of manganese pentacarbonyl compounds

Abstract

Central transition 55Mn NMR spectra of several solid manganese pentacarbonyls acquired at magnetic field strengths of 11.75, 17.63, and 21.1 T are presented. The variety of distinct powder sample lineshapes obtained demonstrates the sensitivity of solid-state 55Mn NMR to the local bonding environment, including the presence of crystallographically unique Mn sites, and facilitates the extraction of the Mn chemical shift anisotropies, CSAs, and the nuclear quadrupolar parameters. The compounds investigated include molecules with approximate C4v symmetry, LMn(CO)5 (L ¼ Cl, Br, I, HgMn(CO)5, CH3) and several molecules of lower symmetry (L ¼ PhCH2, Ph3*nClnSn (n ¼ 1, 2, 3)). For these compounds, the Mn CSA values range from o100 ppm for Cl3SnMn(CO)5 to 1260 ppm for ClMn(CO)5. At 21.1 T the 55Mn NMR lineshapes are appreciably influenced by the Mn CSA despite the presence of significant 55Mn quadrupolar coupling constants that range from 8.0 MHz for Cl3SnMn(CO)5 to 35.0 MHz for CH3Mn(CO)5. The breadth of the solid-state 55Mn NMR spectra of the pentacarbonyl halides is dominated by the CSA at all three applied magnetic fields. DFT calculations of the Mn magnetic shielding tensors reproduce the experimental trends and the magnitude of the CSA is qualitatively rationalized using a molecular orbital,more » MO, interpretation based on Ramsey’s theory of magnetic shielding. In addition to the energy differences between symmetry-appropriate occupied and virtual MOs, the d-character of the Mn MOs is important for determining the paramagnetic shielding contribution to the principal components of the magnetic shielding tensor.« less

Authors:
; ;
Publication Date:
Research Org.:
Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
Sponsoring Org.:
USDOE
OSTI Identifier:
900536
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Chemistry Chemical Physics. PCCP, 9:1226-1238; Journal Volume: 9
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; MANGANESE COMPOUNDS; CARBONYLS; NUCLEAR MAGNETIC RESONANCE; DENSITY FUNCTIONAL METHOD; MANGANESE 55; CHEMICAL SHIFT; MOLECULAR ORBITAL METHOD; Environmental Molecular Sciences Laboratory

Citation Formats

Feindel, Kirk W., Ooms, Kristopher J., and Wasylishen, Roderick E. A solid-state 55Mn NMR spectroscopy and DFT investigation of manganese pentacarbonyl compounds. United States: N. p., 2007. Web. doi:10.1039/b616821c.
Feindel, Kirk W., Ooms, Kristopher J., & Wasylishen, Roderick E. A solid-state 55Mn NMR spectroscopy and DFT investigation of manganese pentacarbonyl compounds. United States. doi:10.1039/b616821c.
Feindel, Kirk W., Ooms, Kristopher J., and Wasylishen, Roderick E. Tue . "A solid-state 55Mn NMR spectroscopy and DFT investigation of manganese pentacarbonyl compounds". United States. doi:10.1039/b616821c.
@article{osti_900536,
title = {A solid-state 55Mn NMR spectroscopy and DFT investigation of manganese pentacarbonyl compounds},
author = {Feindel, Kirk W. and Ooms, Kristopher J. and Wasylishen, Roderick E.},
abstractNote = {Central transition 55Mn NMR spectra of several solid manganese pentacarbonyls acquired at magnetic field strengths of 11.75, 17.63, and 21.1 T are presented. The variety of distinct powder sample lineshapes obtained demonstrates the sensitivity of solid-state 55Mn NMR to the local bonding environment, including the presence of crystallographically unique Mn sites, and facilitates the extraction of the Mn chemical shift anisotropies, CSAs, and the nuclear quadrupolar parameters. The compounds investigated include molecules with approximate C4v symmetry, LMn(CO)5 (L ¼ Cl, Br, I, HgMn(CO)5, CH3) and several molecules of lower symmetry (L ¼ PhCH2, Ph3*nClnSn (n ¼ 1, 2, 3)). For these compounds, the Mn CSA values range from o100 ppm for Cl3SnMn(CO)5 to 1260 ppm for ClMn(CO)5. At 21.1 T the 55Mn NMR lineshapes are appreciably influenced by the Mn CSA despite the presence of significant 55Mn quadrupolar coupling constants that range from 8.0 MHz for Cl3SnMn(CO)5 to 35.0 MHz for CH3Mn(CO)5. The breadth of the solid-state 55Mn NMR spectra of the pentacarbonyl halides is dominated by the CSA at all three applied magnetic fields. DFT calculations of the Mn magnetic shielding tensors reproduce the experimental trends and the magnitude of the CSA is qualitatively rationalized using a molecular orbital, MO, interpretation based on Ramsey’s theory of magnetic shielding. In addition to the energy differences between symmetry-appropriate occupied and virtual MOs, the d-character of the Mn MOs is important for determining the paramagnetic shielding contribution to the principal components of the magnetic shielding tensor.},
doi = {10.1039/b616821c},
journal = {Physical Chemistry Chemical Physics. PCCP, 9:1226-1238},
number = ,
volume = 9,
place = {United States},
year = {Tue Jan 23 00:00:00 EST 2007},
month = {Tue Jan 23 00:00:00 EST 2007}
}