Electron transmission and inner-shell electron energy loss spectroscopy of acetonitrile, isocyanomethane, methyl thiocyanate, and isothiocyanatomethane

Hitchcock, Adam P.; Tronc, M.; Modelli, Alberto

doi:10.1021/j100345a039

Cited by 88 publications

(82 citation statements)

References 6 publications

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“…In the spectra presented in Figure 2 the IPE can be coupled to the oxidation state of the Mn atoms, as has been previously shown by several measurements on different complexes containing Mn in different oxidation states. 52 In our computed spectra the absorption threshold shifts towards higher energies as the oxidation state of the Mn atom increases, in good agreement with the experimental results for the same compounds performed by Yachandra et al 53 The energy position of the threshold, which varies considerably in the three cases, is in fact translated towards increasing energies starting from Mn(II)(acac) 2 eV respectively, with differences of 0.9 and 3.4 eV. The accuracy in determining the shifts from the theoretical curves with the chosen broadening procedure is about ± 0.1 eV.…”

Section: Nexafs K Edge Spectra Of the Reference Mn Compoundssupporting

confidence: 89%

“…It is now possible to correlate specific X-ray features with functional groups and even individual bonds, such that the total spectrum can be considered as a linear combination of elementary spectra -the "building block principle". [1][2][3][4][5] In addition to applications of this principle and other thumb rules, the general development in simulation technology has made it possible to address ever larger systems with complex X-ray spectra, such as biological molecules. Thus, computational studies of the near edge X-ray absorption fine structure (NEXAFS) spectra of amino acids and polypeptides in solution or on surfaces have become common practice.…”

Section: Introductionmentioning

confidence: 99%

“…NEXAFS Mn K edge spectra were generated for Mn in different oxidation states by considering Mn(II), Mn(III) and Mn(IV) reference compounds, for which high quality experimental spectra are available. These complexes, each containing a single Mn atom, are: Mn(II)(acac) 2 …”

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confidence: 99%

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Modeling Near-Edge Fine Structure X-ray Spectra of the Manganese Catalytic Site for Water Oxidation in Photosystem II

2012

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The Mn 1s Near Edge Absorption Fine Structure (NEXAFS) has been computed by means of transition potential gradient corrected Density Functional Theory (DFT) on four Mn 4 Ca clusters modeling the successive S 0 to S 3 steps of the oxygen evolving complex (OEC) in photosystem II (PSII). The model clusters were obtained from a previous theoretical study where they were determined by energy minimization. They are composed of Mn(III) and Mn(IV) atoms, progressing from Mn(III) 3 Mn(IV) for S 0 , to Mn(III) 2 Mn(IV) 2 for S 1 , to Mn(III)Mn(IV) 3 for S 2 , and to * To whom correspondence should be addressed † Uppsala University ‡ Stockholm University ¶ Royal Institute of Technology 1 Mn(IV) 4 for S 3 , implying an Mn centered oxidation during each step of the photosynthetic oxygen evolution. The DFT simulations of the Mn 1s absorption edge reproduce the experimentally measured curves quite well. Using the half-height method, the theoretical IPE's are shifted by 0.93 eV for the S 0 to S 1 transition, by 1.43 eV for the S 1 to S 2 transition, and by 0.63 eV for the S 2 to S 3 transition. The IPE shifts depend strongly on the method used to determine them, and the most interesting result is that the present clusters reproduce the shift in the S 2 to S 3 transition obtained both with the half-height and with the second derivative methods, thus giving strong support to the previously suggested structures and assignments.

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Section: Nexafs K Edge Spectra Of the Reference Mn Compoundssupporting

confidence: 89%

Section: Introductionmentioning

confidence: 99%

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Modeling Near-Edge Fine Structure X-ray Spectra of the Manganese Catalytic Site for Water Oxidation in Photosystem II

2012

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“…However, the energies of u* (S-X) (X = C, 0 , F) orbitals as probed from S 1 s excitation are much less sensitive to bond length changes than the energies of u*(O-X) orbitals (27), suggesting that the u*(C-Se) orbital energy, accessed by C Is, Se 3d, or Se np core excitation, may also be a rather insensitive probe of C-Se bond length.…”

Section: Se 3smentioning

confidence: 99%

Inner-shell excitation studies of conducting organic polymers: selenophene, 3-methyl selenophene, and their polymers

Hitchcock¹,

Tourillon²,

Braun³

1989

Can. J. Chem.

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Inner-shell electron energy loss spectra (ISEELS) of gaseous selenophene and 3-methylselenophene in the regions of Se 3d, Se 3p, Se 3s, and C 1 s are presented and analyzed. The ISEELS spectra are compared to the C 1 s near-edge X-ray absorption fine structure (NEXAFS) spectra of the corresponding polymers deposited electrochemically onto Pt, both with and without doping, to form the electrically conducting state. Methyl substitution at the 3-position of the selenophene ring is found to have little effect on the intensity of the C 1s + n * transition, suggesting that the n manifold is relatively unaffected. The C 1s NEXAFS of thin polyselenophene and poly-3-methylselenophene films confirms that (1) the polymeric chain is composed of the same structural units as the monomers and (2) doping enhances electrical conductivity via a narrowing of the n-n* band gap. Les spectres de perte d'tnergie d'Clectrons en couches internes (ISEELS) du sC1Cnophene et du 3-mCthyl sC1knophkne en phase gaz et aux seuils Se 3d, Se 3p, Se 1s et C Is sont present&. Ces spectres ISEELS sont comparCs aux spectres d'absorption X (NEXAFS) obtenus avec les polymkres correspondants dCposCs Clectrochimiquement en films minces sur une surface de Pt. La substitution en position 3 d'un hydrogkne par un groupement mCthyl affecte trks peu llintensitC de la transition C 1s + n*, suggkrant que les orbitales n e t n * ne sont pas modifiCes. Les spectres NEXAFS des films minces polymCriques confirment que (1) les chaines polymCriques sont composCes des m&mes unit& structurales que les monomkres et que (2) le dopage de ces films vers 1'Ctat conducteur s'accompagne d'un rCtrCcissement de la bande interdite n-n*.

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“…As far as the empty level electronic structure is concerned, experimental data (electron transmission and inner-shell core excitation spectra) have been reported only for methyl isonitrile (CH 3 NC). 22 The goal of this study was to characterize the filled and empty frontier MOs of alkyl and aryl isonitriles in order to gain a better insight into the bonding in their transition metal complexes. The spectral features observed in the UP and ET spectra of 2-propyl (I), tert-butyl (II), 1-butyl (III), 1-pentyl (IV), cyclohexyl (V), 2,6-dimethylphenyl (VI), 4-methoxyphenyl (VII) and 4-chlorophenyl isonitrile (VIII) are assigned to the corresponding MOs with the support of theoretical calculations.…”

Section: Introductionmentioning

confidence: 99%

Donor–acceptor properties of isonitriles studied by photoelectron spectroscopy and electron transmission spectroscopy

2004

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Some alkyl and aryl isonitriles, considered as CO analogue sigma-donor and pi-acceptor ligands in transition metal chemistry, were studied by means of HeI photoelectron spectroscopy and electron transmission spectroscopy, in order to evaluate their donor-acceptor properties from the measured ionization energies (IE) and vertical electron attachment energies (VAE). The investigated molecules were 2-propyl, 1-butyl, tert-butyl, 1-pentyl, cyclohexyl, 2,6-dimethylphenyl, 4-methoxyphenyl and 4-chorophenyl isonitrile. By interpreting the spectra on the basis of literature data and quantum chemical calculations, the spectral features associated with the molecular orbitals mainly involved in coordination and back-donation were identified. The results show that the IE (10.62-10.95 eV) of the sigma electron pair (n(c)) responsible for the sigma-donor capability is substantially lower than that of CO. The VAEs of the empty pi* orbitals involved in the d/pi* back-donation indicate that aryl isonitriles are better acceptors (VAE <0.3 eV) than their aliphatic counterparts (VAE >2.7 eV). In the case of aryl derivatives, the pi-donor ability could also play some role in metal-ligand bonding (IE 8.74-9.34 eV). Isonitrile coordination characteristics are also compared with those of CO, N(2) and CH(3)CN.

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Electron transmission and inner-shell electron energy loss spectroscopy of acetonitrile, isocyanomethane, methyl thiocyanate, and isothiocyanatomethane

Cited by 88 publications

References 6 publications

Modeling Near-Edge Fine Structure X-ray Spectra of the Manganese Catalytic Site for Water Oxidation in Photosystem II

Modeling Near-Edge Fine Structure X-ray Spectra of the Manganese Catalytic Site for Water Oxidation in Photosystem II

Inner-shell excitation studies of conducting organic polymers: selenophene, 3-methyl selenophene, and their polymers

Donor–acceptor properties of isonitriles studied by photoelectron spectroscopy and electron transmission spectroscopy

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