Quantitative studies of davies pulsed ENDOR

Fan, Chaoliang; Doan, Peter E.; Davoust, Clark E.; Hoffman, Brian M.

doi:10.1016/0022-2364(92)90109-k

Cited by 45 publications

(51 citation statements)

References 9 publications

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“…26,27 ENDOR frequencies are given to first order by The peaks are centered at νn (nuclear Larmor frequency) and split by the hyperfine interaction, A, when A is small (A/2 < νn) or centered at A/2 and split by 2νn. Additional quadrupolar interactions (3Pn) are present for nuclei with spin greater than 1 /2, and the observed splitting in the spectrum corresponds to 3Pn (I g m > -I + 1).…”

Section: Methodsmentioning

confidence: 99%

Pulsed ENDOR and ESEEM Study of [Bis(maleonitriledithiolato)nickel]^-: An Investigation into the Ligand Electronic Structure

et al. 1998

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By a combination of Q-band pulsed ENDOR (electron nuclear double resonance) and X-band ESEEM (electron stimulated echo envelope modulation) techniques, we have determined the hyperfine tensors for ethylene (C1) and cyano (C2) carbons and N, of [Ni(mnt)(2)](-), along with the quadrupole tensor for nitrogen. These measurements give pi electron spin densities of rho(C1) approximately 0.03 in the C1 2p(z)() orbital, rho(C2) < 0.003, rho(N) approximately 0.01, such that in total, approximately 0.15 of the spin resides on the ligand atoms C and N, while the rest resides in the NiS(4) core, giving rho(NiS(4)(-)) = 0.85. These results are compared with extended Hückel and density functional (BLYP) MO calculations, as well as with Xalpha calculations reported earlier.

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Section: Methodsmentioning

confidence: 99%

Pulsed ENDOR and ESEEM Study of [Bis(maleonitriledithiolato)nickel]^-: An Investigation into the Ligand Electronic Structure

et al. 1998

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“…The above analysis indicates that NK-ESEEM spectra in the low-turning-angle limit should be described by convolution of an appropriate component lineshape over the envelope function, Ses ij (␦) (Eq. [12]). To match experiment to theory at a particular field, we forced the peak frequencies of a calculated spectrum, ij obs , to match those measured for the experimental one and report the theoretical values of the ij max given by the calculation (Fig.…”

Section: Fig 2 Field Dependence Of Fractional Three-pulse Nk-eseem mentioning

confidence: 93%

“…4), and therefore the spectra are modeled with Eqs. [10] ( 3 0) through [12], which are appropriate for such a linear variation (and whose use does not require the low-field condition utilized in the derivation). This calculation is illustrated in the inset to [12]), as well as the peak obtained from it by convolution.…”

Section: Fig 2 Field Dependence Of Fractional Three-pulse Nk-eseem mentioning

confidence: 98%

“…The function, Eq. [12], and the final peak shape obtained by convolution are illustrated in the inset to Fig. 4.…”

Section: Nk-eseem Endor Envelopesmentioning

confidence: 99%

“…X-band ESEEM and ENDOR spectra were acquired at 2 K with a laboratorybuilt spectrometer described elsewhere (12). As before (6,8), a static field, B 0 , oriented parallel to the B 1 field, was produced by a pair of Helmholtz coils mounted around the tail of a liquid helium immersion dewar.…”

Section: A Solution Of [Fe(ii)edta]mentioning

confidence: 99%

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Non-Kramers ENDOR and ESEEM of the S = 2 Ferrous Ion of [Fe(II)EDTA]2−

Song

Doan

Gurbiel

et al. 1999

Journal of Magnetic Resonance

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Electron‐Nuclear Double Resonance (ENDOR) Spectroscopy

Telser

2005

Encyclopedia of Inorganic Chemistry

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Electron‐nuclear double resonance (ENDOR) spectroscopy is a magnetic resonance technique that was invented in the mid 1950s by George Feher, then at Bell Telephone Laboratories. The first applications of ENDOR were to problems in solid state physics, but beginning in the 1970s, and particularly since the late 1980s, ENDOR has been widely applied to bioinorganic systems. ENDOR is fundamentally an electron paramagnetic resonance (EPR) technique, however, it also has aspects of nuclear magnetic resonance (NMR) spectroscopy. Essentially, ENDOR consists of the monitoring of an EPR signal, while effecting NMR transitions. The EPR signal can be either a continuous wave (CW) signal or a pulsed, electron spin echo (ESE) signal, in both cases caused by the application of microwave energy to a sample in an external magnetic field. As with EPR itself, ENDOR can thus be either a CW or pulsed (time‐domain) spectroscopic technique. The NMR transitions are caused by the application of radiofrequency (rf) energy, as with NMR itself. NMR transitions only of nuclei magnetically (hyperfine) coupled to the paramagnetic center (i.e., the center giving rise to the EPR signal) affect the intensity of this EPR signal, whether CW or pulsed, and provide characteristic ENDOR spectra. As a consequence of its double resonance nature, ENDOR has a great deal of flexibility in spectroscopic parameters. The parameters that affect EPR signals, e.g., microwave power, can also play a role in ENDOR spectral appearance. Additionally, there are parameters relevant to the NMR aspects of ENDOR that affect ENDOR spectra. In both CW and pulsed ENDOR there is experimental flexibility, which is described here. As a result, ENDOR spectroscopy can provide detailed information on multiple, magnetically active nuclei that comprise a paramagnetic center in a bioinorganic system. This information includes identification of such nuclei and metrical information on their relation to the paramagnetic center. This article uses a multifaceted case study to illustrate the application of ENDOR spectroscopy in bioinorganic chemistry. Specifically, the case study describes the application of multinuclear ( 1, 2 H, 13 C, 57 Fe, 95 Mo) CW and pulsed ENDOR to enhance our understanding of the iron–molybdenum cofactor in nitrogenase. ENDOR allows identification of the constituent metal ions and their formal oxidation states, and identifies the nature of the substrate analog or inhibitor binding to the cluster. In combination with resting state structural information, and computational and model system studies, ENDOR can provide a structural picture of the intermediates in nitrogen fixation.

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Quantitative studies of davies pulsed ENDOR

Cited by 45 publications

References 9 publications

Pulsed ENDOR and ESEEM Study of [Bis(maleonitriledithiolato)nickel]^-: An Investigation into the Ligand Electronic Structure

Pulsed ENDOR and ESEEM Study of [Bis(maleonitriledithiolato)nickel]^-: An Investigation into the Ligand Electronic Structure

Non-Kramers ENDOR and ESEEM of the S = 2 Ferrous Ion of [Fe(II)EDTA]2−

Electron‐Nuclear Double Resonance (ENDOR) Spectroscopy

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Quantitative studies of davies pulsed ENDOR

Cited by 45 publications

References 9 publications

Pulsed ENDOR and ESEEM Study of [Bis(maleonitriledithiolato)nickel]-: An Investigation into the Ligand Electronic Structure

Pulsed ENDOR and ESEEM Study of [Bis(maleonitriledithiolato)nickel]-: An Investigation into the Ligand Electronic Structure

Non-Kramers ENDOR and ESEEM of the S = 2 Ferrous Ion of [Fe(II)EDTA]2−

Electron‐Nuclear Double Resonance (ENDOR) Spectroscopy

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Pulsed ENDOR and ESEEM Study of [Bis(maleonitriledithiolato)nickel]^-: An Investigation into the Ligand Electronic Structure

Pulsed ENDOR and ESEEM Study of [Bis(maleonitriledithiolato)nickel]^-: An Investigation into the Ligand Electronic Structure