Magnetic Circular Dichroism of the Hydroxyl Radical in an Argon Matrix

Langford, Vaughan S.; Williamson, Bryce E.

doi:10.1021/jp970076q

Cited by 20 publications

(48 citation statements)

References 33 publications

(45 reference statements)

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“…• . 63 This oxyl species reacts reversibly with O 2 to form stable ozonide ( • ), where O L means the zeolite lattice oxygen at the Al site. This reactivity is attributed to Zn II −O t ground-state bonding.…”

Section: Introductionsupporting

confidence: 77%

Room-Temperature Activation of the C–H Bond in Methane over Terminal Zn^II–Oxyl Species in an MFI Zeolite: A Combined Spectroscopic and Computational Study of the Reactive Frontier Molecular Orbitals and Their Origins

et al. 2018

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Oxygenase reactivity toward selective partial oxidation of CH 4 to CH 3 OH requires an atomic oxygen-radical bound to metal (M−O • : oxyl intermediate) that is capable of abstracting an H atom from the significantly strong C−H bond in CH 4 . Because such a reaction is frequently observed in metal-doped zeolites, it has been recognized that the zeolite provides an environment that stabilizes the M−O • intermediate. However, no experimental data of M−O • have so far been discovered in the zeolite; thus, little is known about the correlation among the state of M−O • , its reactivity for CH 4 , and the nature of the zeolite environment. Here, we report a combined spectroscopic and computational study of the room-temperature activation of CH 4 over Zn II −O • in the MFI zeolite. One Zn II −O • species does perform H-abstraction from CH 4 at room temperature. The resultant CH 3• species reacts with the other Zn II −O • site to form the Zn II −OCH 3 species. The H 2 Oassisted extraction of surface methoxide yields 29 μmol g −1 of CH 3 OH with a 94% selectivity. The quantum mechanics (QM)/ molecular mechanics (MM) calculation determined the central step as the oxyl-mediated hydrogen atom transfer which requires an activation energy of only 10 kJ mol −1 . On the basis of the findings in gas-phase experiments regarding the CH 4 activation by the free [M−O • ] + species, the remarkable H-abstraction reactivity of the Zn II −O • species in zeolites was totally rationalized. Additionally, the experimentally validated QM/MM calculation revealed that the zeolite lattice has potential as the ligand to enhance the polarization of the M−O • bond and thereby enables to create effectively the highly reactive M−O • bond required for low-temperature activation of CH 4 . The present study proposes that tuning of the polarization effect of the anchoring site over heterogeneous catalysts is the valuable way to create the oxyl-based functionality on the heterogeneous catalyst.

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Section: Introductionsupporting

confidence: 77%

Room-Temperature Activation of the C–H Bond in Methane over Terminal Zn^II–Oxyl Species in an MFI Zeolite: A Combined Spectroscopic and Computational Study of the Reactive Frontier Molecular Orbitals and Their Origins

et al. 2018

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“…We have investigated the MCD of Mn 12 SMM's using a spectrometer that is described elsewhere. 11 We show here that this spectroscopic technique is not only related with magnetization but permits effectively the same measurements as SQUID magnetometry, as it can be inferred by comparision of quantitative description of MCD shown by McInnes et al with Eqs. ͑2͒,͑3͒.…”

supporting

confidence: 69%

Magnetism of isolatedMn12single-molecule magnets detected by magnetic circular dichroism: Observation of spin tunneling with a magneto-optical technique

et al. 2004

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We report magnetic and magneto-optical measurements of two Mn 12 single-molecule magnet derivatives isolated in organic glasses. Field-dependent magnetic circular dichroism ͑MCD͒ intensity curves ͑hysteresis cycles͒ are found to be essentially identical to superconducting quantum interference device magnetization results and provide experimental evidence for the potential of the optical technique for magnetic characterization. Optical observation of magnetic tunneling has been achieved by studying the decay of the MCD signal at weak applied magnetic field.

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“…For the calculation of I n MCD it is necessary to transform the operators M Ϯ1 and the ket-vector ͉ M s A ͘ from the laboratoryfixed to a molecule-fixed reference frame: 41,42 ͉͗ n…”

Section: B MCD Spectramentioning

confidence: 99%

Relativistic Jahn–Teller effects in the quartet states of K3 and Rb3: A vibronic analysis of the 2 E4′←1 A42′ electronic transitions based on ab initio calculations

Hauser

Auböck

Callegari

et al. 2010

The Journal of Chemical Physics

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We apply second-order multireference Rayleigh-Schrodinger perturbation theory to obtain the adiabatic potential energy surface of the 1 (4)A(2)(') lowest quartet state and the 2 (4)E(') excited state of K(3) and Rb(3). Both trimers show a typical Emultiply sign in circlee Jahn-Teller distortion in their 2 (4)E(') state, which is analyzed in terms of relativistic Jahn-Teller effect theory. Linear, quadratic, and spin-orbit coupling terms are extracted from the ab initio results and used to generate simulated spectra for a direct comparison with laser-induced fluorescence and magnetic circular dichroism spectra of alkali-doped helium nanodroplets [Aubock et al., J. Chem. Phys. 129, 114501 (2008)].

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Magnetic Circular Dichroism of the Hydroxyl Radical in an Argon Matrix

Cited by 20 publications

References 33 publications

Room-Temperature Activation of the C–H Bond in Methane over Terminal Zn^II–Oxyl Species in an MFI Zeolite: A Combined Spectroscopic and Computational Study of the Reactive Frontier Molecular Orbitals and Their Origins

Room-Temperature Activation of the C–H Bond in Methane over Terminal Zn^II–Oxyl Species in an MFI Zeolite: A Combined Spectroscopic and Computational Study of the Reactive Frontier Molecular Orbitals and Their Origins

Magnetism of isolatedMn12single-molecule magnets detected by magnetic circular dichroism: Observation of spin tunneling with a magneto-optical technique

Relativistic Jahn–Teller effects in the quartet states of K3 and Rb3: A vibronic analysis of the 2 E4′←1 A42′ electronic transitions based on ab initio calculations

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Magnetic Circular Dichroism of the Hydroxyl Radical in an Argon Matrix

Cited by 20 publications

References 33 publications

Room-Temperature Activation of the C–H Bond in Methane over Terminal ZnII–Oxyl Species in an MFI Zeolite: A Combined Spectroscopic and Computational Study of the Reactive Frontier Molecular Orbitals and Their Origins

Room-Temperature Activation of the C–H Bond in Methane over Terminal ZnII–Oxyl Species in an MFI Zeolite: A Combined Spectroscopic and Computational Study of the Reactive Frontier Molecular Orbitals and Their Origins

Magnetism of isolatedMn12single-molecule magnets detected by magnetic circular dichroism: Observation of spin tunneling with a magneto-optical technique

Relativistic Jahn–Teller effects in the quartet states of K3 and Rb3: A vibronic analysis of the 2 E4′←1 A42′ electronic transitions based on ab initio calculations

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Room-Temperature Activation of the C–H Bond in Methane over Terminal Zn^II–Oxyl Species in an MFI Zeolite: A Combined Spectroscopic and Computational Study of the Reactive Frontier Molecular Orbitals and Their Origins

Room-Temperature Activation of the C–H Bond in Methane over Terminal Zn^II–Oxyl Species in an MFI Zeolite: A Combined Spectroscopic and Computational Study of the Reactive Frontier Molecular Orbitals and Their Origins