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Title: Effect of magnetic fields on the methyl rotation in a paramagnetic cobalt(ii) complex. Quasielastic neutron scattering studies

Abstract

Molecular dynamics is a fundamental property of metal complexes. These dynamic processes, especially for paramagnetic complexes under external magnetic fields, are in general not well understood. Quasielastic neutron scattering (QENS) in 0–4 T magnetic fields has been used to study the dynamics of Co(acac) 2(D 2O) 2 (1- d 4, acac = acetylacetonate). At 80–100 K, rotation of the methyl groups on the acac ligands is the dominant dynamical process. This rotation is slowed down by the magnetic field increase. Rotation times at 80 K are 5.6(3) × 10 –10 s at 0 T and 2.04(10) × 10 –9 s at 4 T. The QENS studies suggest that methyl groups in these paramagnetic Co(II) molecules do not behave as isolated units, which is consistent with results from earlier magnetic susceptibility studies indicating the presence of intermolecular interactions. DFT calculations show that unpaired electron spin density in 1 is dispersed to the atoms of both acac and H 2O ligands. Methyl torsions in 1- d 4 have also been observed at 5–100 K in inelastic neutron spectroscopy (INS). In conclusion, the QENS and INS results here help understand the dynamics of the compound in the solid state.

Authors:
 [1]; ORCiD logo [2];  [1]; ORCiD logo [2];  [2]; ORCiD logo [2]; ORCiD logo [1]
  1. Univ. of Tennessee, Knoxville, TN (United States)
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1484105
Alternate Identifier(s):
OSTI ID: 1463037
Grant/Contract Number:  
AC05-00OR22725
Resource Type:
Accepted Manuscript
Journal Name:
Physical Chemistry Chemical Physics. PCCP (Print)
Additional Journal Information:
Journal Name: Physical Chemistry Chemical Physics. PCCP (Print); Journal Volume: 20; Journal Issue: 32; Journal ID: ISSN 1463-9076
Publisher:
Royal Society of Chemistry
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Stavretis, Shelby E., Mamontov, Eugene, Moseley, Duncan H., Cheng, Yongqiang, Daemen, Luke L., Ramirez-Cuesta, Anibal J., and Xue, Zi -Ling. Effect of magnetic fields on the methyl rotation in a paramagnetic cobalt(ii) complex. Quasielastic neutron scattering studies. United States: N. p., 2018. Web. doi:10.1039/c8cp01660g.
Stavretis, Shelby E., Mamontov, Eugene, Moseley, Duncan H., Cheng, Yongqiang, Daemen, Luke L., Ramirez-Cuesta, Anibal J., & Xue, Zi -Ling. Effect of magnetic fields on the methyl rotation in a paramagnetic cobalt(ii) complex. Quasielastic neutron scattering studies. United States. doi:10.1039/c8cp01660g.
Stavretis, Shelby E., Mamontov, Eugene, Moseley, Duncan H., Cheng, Yongqiang, Daemen, Luke L., Ramirez-Cuesta, Anibal J., and Xue, Zi -Ling. Fri . "Effect of magnetic fields on the methyl rotation in a paramagnetic cobalt(ii) complex. Quasielastic neutron scattering studies". United States. doi:10.1039/c8cp01660g. https://www.osti.gov/servlets/purl/1484105.
@article{osti_1484105,
title = {Effect of magnetic fields on the methyl rotation in a paramagnetic cobalt(ii) complex. Quasielastic neutron scattering studies},
author = {Stavretis, Shelby E. and Mamontov, Eugene and Moseley, Duncan H. and Cheng, Yongqiang and Daemen, Luke L. and Ramirez-Cuesta, Anibal J. and Xue, Zi -Ling},
abstractNote = {Molecular dynamics is a fundamental property of metal complexes. These dynamic processes, especially for paramagnetic complexes under external magnetic fields, are in general not well understood. Quasielastic neutron scattering (QENS) in 0–4 T magnetic fields has been used to study the dynamics of Co(acac)2(D2O)2 (1-d4, acac = acetylacetonate). At 80–100 K, rotation of the methyl groups on the acac ligands is the dominant dynamical process. This rotation is slowed down by the magnetic field increase. Rotation times at 80 K are 5.6(3) × 10–10 s at 0 T and 2.04(10) × 10–9 s at 4 T. The QENS studies suggest that methyl groups in these paramagnetic Co(II) molecules do not behave as isolated units, which is consistent with results from earlier magnetic susceptibility studies indicating the presence of intermolecular interactions. DFT calculations show that unpaired electron spin density in 1 is dispersed to the atoms of both acac and H2O ligands. Methyl torsions in 1-d4 have also been observed at 5–100 K in inelastic neutron spectroscopy (INS). In conclusion, the QENS and INS results here help understand the dynamics of the compound in the solid state.},
doi = {10.1039/c8cp01660g},
journal = {Physical Chemistry Chemical Physics. PCCP (Print)},
number = 32,
volume = 20,
place = {United States},
year = {2018},
month = {7}
}

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Works referenced in this record:

Electronic structure and magnetic properties of high-spin octahedral Co(II) complexes: Co(II)(acac)2(H2O)2
journal, December 1999

  • Lohr, Lawrence L.; Miller, Jeremy C.; Sharp, Robert R.
  • The Journal of Chemical Physics, Vol. 111, Issue 22
  • DOI: 10.1063/1.480365

Methyl rotational potentials of trimethyl metal compounds studied by inelastic and quasielastic neutron scattering
journal, August 2003


Generalized Gradient Approximation Made Simple
journal, October 1996

  • Perdew, John P.; Burke, Kieron; Ernzerhof, Matthias
  • Physical Review Letters, Vol. 77, Issue 18, p. 3865-3868
  • DOI: 10.1103/PhysRevLett.77.3865

DAVE: A Comprehensive Software Suite for the Reduction, Visualization, and Analysis of Low Energy Neutron Spectroscopic Data
journal, November 2009

  • Azuah, Richard Tumanjong; Kneller, Larry R.; Qiu, Yiming
  • Journal of Research of the National Institute of Standards and Technology, Vol. 114, Issue 6
  • DOI: 10.6028/jres.114.025

Salt-Induced Universal Slowing Down of the Short-Time Self-Diffusion of a Globular Protein in Aqueous Solution
journal, June 2015

  • Grimaldo, Marco; Roosen-Runge, Felix; Hennig, Marcus
  • The Journal of Physical Chemistry Letters, Vol. 6, Issue 13
  • DOI: 10.1021/acs.jpclett.5b01073

Protein self-diffusion in crowded solutions
journal, July 2011

  • Roosen-Runge, F.; Hennig, M.; Zhang, F.
  • Proceedings of the National Academy of Sciences, Vol. 108, Issue 29
  • DOI: 10.1073/pnas.1107287108

Projector augmented-wave method
journal, December 1994


Exposing the intermolecular nature of the second relaxation pathway in a mononuclear cobalt( ii ) single-molecule magnet with positive anisotropy
journal, January 2015

  • Habib, Fatemah; Korobkov, Ilia; Murugesu, Muralee
  • Dalton Transactions, Vol. 44, Issue 14
  • DOI: 10.1039/C5DT00258C

Intensities of Electronic Transitions in Molecular Spectra IV. Cyclic Dienes and Hyperconjugation
journal, May 1939

  • Mulliken, Robert S.
  • The Journal of Chemical Physics, Vol. 7, Issue 5
  • DOI: 10.1063/1.1750446

Magnetic relaxations in a Tb-based single molecule magnet studied by quasielastic neutron scattering
journal, December 2013


C HEMICAL A PPLICATIONS OF N EUTRON S CATTERING
journal, October 1999


The rise of 3-d single-ion magnets in molecular magnetism: towards materials from molecules?
journal, January 2016

  • Frost, Jamie M.; Harriman, Katie L. M.; Murugesu, Muralee
  • Chemical Science, Vol. 7, Issue 4
  • DOI: 10.1039/C5SC03224E

Theoretical Analysis of the Rotational Barrier of Ethane
journal, February 2007

  • Mo, Yirong; Gao, Jiali
  • Accounts of Chemical Research, Vol. 40, Issue 2
  • DOI: 10.1021/ar068073w

Spin density distribution in transition metal complexes
journal, December 2005

  • Ruiz, Eliseo; Cirera, Jordi; Alvarez, Santiago
  • Coordination Chemistry Reviews, Vol. 249, Issue 23
  • DOI: 10.1016/j.ccr.2005.04.010

The Entropy of Ethane and the Third Law of Thermodynamics. Hindered Rotation of Methyl Groups
journal, February 1937

  • Kemp, J. D.; Pitzer, Kenneth S.
  • Journal of the American Chemical Society, Vol. 59, Issue 2
  • DOI: 10.1021/ja01281a014

Room temperature quantum coherence in a potential molecular qubit
journal, October 2014

  • Bader, Katharina; Dengler, Dominik; Lenz, Samuel
  • Nature Communications, Vol. 5, Issue 1
  • DOI: 10.1038/ncomms6304

From ultrasoft pseudopotentials to the projector augmented-wave method
journal, January 1999


Molecular magnetic hysteresis at 60 kelvin in dysprosocenium
journal, August 2017

  • Goodwin, Conrad A. P.; Ortu, Fabrizio; Reta, Daniel
  • Nature, Vol. 548, Issue 7668
  • DOI: 10.1038/nature23447

First-principles prediction of redox potentials in transition-metal compounds with LDA + U
journal, December 2004


trans -W(Cmesityl)(dmpe) 2 H:  Revealing a Highly Polar W−H Bond and H-Mobility in Liquid and Solid State
journal, June 2007

  • Zou, Fenglou; Furno, Franck; Fox, Thomas
  • Journal of the American Chemical Society, Vol. 129, Issue 22
  • DOI: 10.1021/ja069140k

Direct Observation of an Equilibrium between (Bu t CH 2 ) 2 W(⋮CBu t )(SiBu t Ph 2 ) and (Bu t CH 2 )W(CHBu t ) 2 (SiBu t Ph 2 ) and an Unusual Silyl Migration
journal, December 1998

  • Chen, Tianniu; Wu, Zhongzhi; Li, Liting
  • Journal of the American Chemical Society, Vol. 120, Issue 51
  • DOI: 10.1021/ja982571l

The Torsion Oscillator-Rotator in the Quantum Mechanics
journal, May 1932


Thermodynamic Functions for Molecules Having Restricted Internal Rotations
journal, June 1937

  • Pitzer, Kenneth S.
  • The Journal of Chemical Physics, Vol. 5, Issue 6
  • DOI: 10.1063/1.1750058

Molecular spin qudits for quantum algorithms
journal, January 2018

  • Moreno-Pineda, Eufemio; Godfrin, Clément; Balestro, Franck
  • Chemical Society Reviews, Vol. 47, Issue 2
  • DOI: 10.1039/C5CS00933B

Structural Information from Methyl Internal Rotation Spectroscopy
journal, October 1997


Spin–phonon couplings in transition metal complexes with slow magnetic relaxation
journal, July 2018

  • Moseley, Duncan H.; Stavretis, Shelby E.; Thirunavukkuarasu, Komalavalli
  • Nature Communications, Vol. 9, Issue 1
  • DOI: 10.1038/s41467-018-04896-0

In Vivo Protein Dynamics on the Nanometer Length Scale and Nanosecond Time Scale
journal, April 2017

  • Anunciado, Divina B.; Nyugen, Vyncent P.; Hurst, Gregory B.
  • The Journal of Physical Chemistry Letters, Vol. 8, Issue 8
  • DOI: 10.1021/acs.jpclett.7b00399

Structure and Dynamics of Octamethyl-POSS Nanoparticles
journal, February 2014

  • Jalarvo, Niina; Gourdon, Olivier; Ehlers, Georg
  • The Journal of Physical Chemistry C, Vol. 118, Issue 10
  • DOI: 10.1021/jp412228r

Determining Key Local Vibrations in the Relaxation of Molecular Spin Qubits and Single-Molecule Magnets
journal, March 2017

  • Escalera-Moreno, L.; Suaud, N.; Gaita-Ariño, A.
  • The Journal of Physical Chemistry Letters, Vol. 8, Issue 7
  • DOI: 10.1021/acs.jpclett.7b00479

Incorporation of aspirin modulates the dynamical and phase behavior of the phospholipid membrane
journal, January 2017

  • Sharma, V. K.; Mamontov, E.; Ohl, M.
  • Physical Chemistry Chemical Physics, Vol. 19, Issue 3
  • DOI: 10.1039/C6CP06202D

13C NMR evidence for Fermi-contact interaction and spin delocalization on the ligands in the nanomagnet MN12O12-acetate
journal, January 2002


Studies of U(C 5 H 5 ) 3 Cl: Reorientational motions of cyclopentadienyl rings
journal, February 1994


Origin of Methyl Internal Rotation Barriers
journal, December 1999

  • Goodman, Lionel; Pophristic, Vojislava; Weinhold, Frank
  • Accounts of Chemical Research, Vol. 32, Issue 12
  • DOI: 10.1021/ar990069f

Molecular spin-orbit excitations in the J eff = 1 2 frustrated spinel GeCo 2 O 4
journal, August 2011


Origin of slow magnetic relaxation in Kramers ions with non-uniaxial anisotropy
journal, July 2014

  • Gómez-Coca, Silvia; Urtizberea, Ainhoa; Cremades, Eduard
  • Nature Communications, Vol. 5, Issue 1
  • DOI: 10.1038/ncomms5300

13 C NMR and relaxation studies of the nanomagnet Mn 12 -acetate
journal, July 2001


Millisecond Coherence Time in a Tunable Molecular Electronic Spin Qubit
journal, December 2015


Microscopic relaxations in a protein sustained down to 160 K in a non-glass forming organic solvent
journal, January 2017


A time-of-flight backscattering spectrometer at the Spallation Neutron Source, BASIS
journal, August 2011

  • Mamontov, E.; Herwig, K. W.
  • Review of Scientific Instruments, Vol. 82, Issue 8
  • DOI: 10.1063/1.3626214

Forging Solid-State Qubit Design Principles in a Molecular Furnace
journal, February 2017