<b>Activation Energies for Reorientation Processes in Ferrocene and Some of its Derivatives: A Study of Proton Magnetic Resonance Spectra</b>

Mulay, L. N.; Attalla, A.

doi:10.1021/ja00889a013

Cited by 67 publications

(16 citation statements)

References 2 publications

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“…The barrier to reorientation of cyclopentadienyl rings in crystalline ferrocene has been estimated from NMR data (temperature dependence of line width and of spin-lattice relaxation times). Values in the range 7.5-9.6 kJ mo1-1 have been reported for the LT phase (Holm & Ibers, 1959;Mulay & Attalla, 1963;Campbell, Fyfe, Harold-Smith & Jeffrey, 1976). © 1979 International Union of Crystallography Above the phase transition the barrier appears to become smaller.…”

Section: Introductionmentioning

confidence: 95%

A new interpretation of the disordered crystal structure of ferrocene

Seiler¹,

Dunitz²

1979

Acta Crystallogr B Struct Crystallogr Cryst Chem

337

138

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X-ray analyses of ferrocene [Fe(CsHs) 2, CmH~0Fe] at room temperature and at 173 K yield vibrationalellipsoid patterns that are incompatible with pure rotational disorder of the cyclopentadienyl rings. Below 164 K ferrocene becomes triclinic. Relationships between the diffraction patterns of the monoclinic hightemperature (HT) and triclinic low-temperature (LT) structures suggest that the formally centrosymmetric molecule of the disordered HT phase can be described in good approximation as an averaged superposition of the four molecules present in the primitive LT cell. The molecular centre of symmetry required by the HT space group is thus only statistical in nature, and the crystallographic evidence for the staggered arrangement of the cyclopentadienyl rings in ferrocene and other isomorphous metallocenes has to be revised.

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Section: Introductionmentioning

confidence: 95%

A new interpretation of the disordered crystal structure of ferrocene

Seiler¹,

Dunitz²

1979

Acta Crystallogr B Struct Crystallogr Cryst Chem

337

138

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“…) as the curing agent, we argued that the facile torsional motion of ferrocene leads to the observed reduction in cure stress as well as unique stress relaxation properties . The Cp ligands are known to have very low rotation barriers around the Cp─Fe bond (5.0–9.6 kJ/mol for the monoclinic phase), and thus provide a mechanism for torsional‐induced relaxation. Ferrocene has been incorporated into multiple polymer materials including both side‐chain polymers (ferrocene as a pendant group) and main‐chain polymers (ferrocene as part of the backbone) .…”

Section: Introductionmentioning

confidence: 99%

Investigating Chain Dynamics in Highly Crosslinked Polymers using Solid‐State ¹H NMR Spectroscopy

Alam

Jones

2019

J Polym Sci B Polym Phys

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Solid state 1H NMR line‐shape analysis and (double quantum) DQ 1H NMR experiments have been used to investigate the segmental and polymer chain dynamics as a function of temperature for a series of thermosetting epoxy resins produced using different diamine curing agents. In these thermosets, chemical crosslinks introduce topological constraints leading to residual stresses during curing. Materials containing a unique ferrocene‐based diamine (FcDA) curing agent were evaluated to address the role of the ferrocene fluxional process on the atomic‐level polymer dynamics. At temperatures above the glass transition temperature (Tg), the DQ 1H NMR experiments provided a measure of the relative effective crosslink and entanglement densities for these materials and revealed significant polymer chain dynamic heterogeneity in the FcDA‐cured thermosets. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019, 57, 1143–1156

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“…A typical example is ferrocene, whose ring dynamics in the pure solid has been extensively investigated by Downloaded by [York University Libraries] at 21:06 17 November 2014 1H-N.M.R. [3][4][5][6]19]. The activation energies evaluated from the temperature dependences of the proton spin-lattice relaxation time T1 in different crystal modifications clearly demonstrate the influence of the crystal field [19].…”

Section: Discussionmentioning

confidence: 99%

“…A closely related motional process is found in many sandwich compounds, where the aromatic rings exhibit uniaxial fast reorientation at room temperature. The temperature dependence of the proton spin-lattice relaxation time and of the second moment of triclinic ferrocene (Fe(cp)2) powder, for example, has been traced back to a hindered rotation of the cyclopentadienyl rings around their five-fold axes [3][4][5][6]. 586 R. Wolf et al…”

Section: Introductionmentioning

confidence: 99%

ENDOR on vanadium d⁵-sandwich compounds

1984

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The temperature dependence of the proton ENDOR spectra of dibenzene vanadium diluted into (2,2)-paracyclophane and ruthenocene single crystals is reported in the range 10-200 K. The low temperature spectra are discussed in detail in the preceding paper. The observed temperature dependence is modelled by a chemical exchange formalism for the rotational reorientation of the benzene rings with respect to the matrix crystal, leading to estimates of the activation parameters of the reorientation process. In the (2,2)-paracyclophane host crystal, both rings of dibenzene vanadium show the same reorientation dynamics, whereas in the ruthenocene host crystal, the corresponding activation parameters of the two benzene rings are considerably different. Furthermore, from the temperature dependence of the proton ENDOR spectra of dibenzene vanadium and cyclopentadienylcycloheptatrienyl vanadium in frozen toluene, the effect of ring size on the rotational reorientation dynamics is demonstrated.

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Activation Energies for Reorientation Processes in Ferrocene and Some of its Derivatives: A Study of Proton Magnetic Resonance Spectra

Cited by 67 publications

References 2 publications

A new interpretation of the disordered crystal structure of ferrocene

A new interpretation of the disordered crystal structure of ferrocene

Investigating Chain Dynamics in Highly Crosslinked Polymers using Solid‐State ¹H NMR Spectroscopy

ENDOR on vanadium d⁵-sandwich compounds

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Activation Energies for Reorientation Processes in Ferrocene and Some of its Derivatives: A Study of Proton Magnetic Resonance Spectra

Cited by 67 publications

References 2 publications

A new interpretation of the disordered crystal structure of ferrocene

A new interpretation of the disordered crystal structure of ferrocene

Investigating Chain Dynamics in Highly Crosslinked Polymers using Solid‐State 1H NMR Spectroscopy

ENDOR on vanadium d5-sandwich compounds

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Product

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Investigating Chain Dynamics in Highly Crosslinked Polymers using Solid‐State ¹H NMR Spectroscopy

ENDOR on vanadium d⁵-sandwich compounds