| 21. |
- Liu, T. B., et al.
(författare)
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Synthesis, structures and electrochemical properties of nitro- and amino-functionalized diiron azadithiolates as active site models of Fe-only hydrogenases
- 2004
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Ingår i: Chemistry - A European Journal. - : Wiley. - 0947-6539 .- 1521-3765. ; 10:18, s. 4474-4479
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Tidskriftsartikel (refereegranskat)abstract
- Complex [{(mu-SCH2)(2)N(4-NO2C6H4)}Fe-2(CO)(6)] (4) was prepared by the reaction of the dianionic intermediate [(mu-S)(2)Fe-2(CO)(6)](2-) and N,N-bis(chloromethyl)-4-nitroaniline as a biomimetic model of the active site of Fe-only hydrogenase. The reduction of 4 by Pd-C/H-2 under a neutral condition afforded complex [{(mu-SCH2)(2)N(4-NH2C6H4)}Fe-2(CO)(6)] (5) in 67% yield. Both complexes were characterized by IR, H-1 and C-13 NMR spectroscopy and MS spectrometry. The molecular structure of 4, as determined by X-ray analysis, has a butterfly 2Fe2S core and the aryl group on the bridged-N atom slants to the Fe(2) site. Cyclic voltammograms of 4 and 5 were studied to evaluate their redox properties. It was found that complex 4 catalyzed electrochemical proton reduction in the presence of acetic acid. A plausible mechanism of the electrocatalytic proton reduction is discussed.
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| 22. |
- Ma, C. B., et al.
(författare)
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Great framework variation of polymers in the manganese(II) maleate/alpha,alpha' - Diimine system : Syntheses, structures, and magneto-structural correlation
- 2003
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Ingår i: European Journal of Inorganic Chemistry. - : Wiley. - 1434-1948 .- 1099-1948 .- 1099-0682. ; :15, s. 2872-2879
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Tidskriftsartikel (refereegranskat)abstract
- Three novel manganese(II) coordination polymers, [Mn (maleate)(phen)](n) (1; phen = 1,10-phenanthroline), [Mn-(maleate)(phen)](n).nH(2)O (2), and [Mn(maleate)(bpy)](n) (3; bpy = 2,2'-bipyridine), have been synthesized by treatment of Mn2+ with maleic acid with participation of chelate diimine ligands, and have been identified by single-crystal, X-ray diffraction to have either one-dimensional (1D) zigzag chain structures (1 and 2) or a two-dimensional (2D) sinuous layer structure (3). Each maleate dianion coordinates to three Mn centers, in different bridging modes (syn-anti in 1 and 2, syn-syn and anti-anti in 3). These compounds represent an interesting example of structural topology variation from 1D to 2D mediated by chemically similar auxiliary chelate ligands. Variable-temperature magnetic susceptibility measurements show weak anti-ferromagnetic exchange interactions between the adjacent Mn-II ions, with J = -0.06 cm(-1) (2) and J = -1.3 cm(-1), zJ' = -0.27 cm(-1) (3). The differences in the magnitudes of these coupling interactions agree well with the nature of the carb oxylate-bridging coordination of maleate.
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| 23. |
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| 24. |
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| 25. |
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| 26. |
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| 27. |
- Sun, Z. G, et al.
(författare)
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Femtosecond pump-probe photodissociation of OClO: direct observation of the (2)A(1) state and the role of accidental multiphoton resonance
- 2004
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Ingår i: Chemical Physics Letters. - : Elsevier BV. - 0009-2614. ; 393:1-3, s. 204-208
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Tidskriftsartikel (refereegranskat)abstract
- Previous pump-probe experiments on the OCIO molecule are analyzed and a consistent interpretation of the experimental observations is proposed. We demonstrate that a direct observation of the very weak (2)A(1) state of OCIO is possible with a proper femtosecond pulse, and suggest that it is necessary to introduce an accidental resonance of the probe pulse with the highly excited D or E states for understanding the observed distinct photodissociation dynamics of the (2)A(2) state using pump pulses of slightly different wavelengths. A transient abnormal peak, observed in the OCIO+ ion signal after a stronger excitation, is also convincingly interpreted. (C) 2004 Elsevier B.V. All rights reserved.
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| 28. |
- Sun, Z. G, et al.
(författare)
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Time-dependent wave packet split operator calculations on a three-dimensional Fourier grid in Radau coordinates applied to the OCIO photoelectron spectrum
- 2004
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Ingår i: Journal of Physical Chemistry A. - : American Chemical Society (ACS). - 1089-5639 .- 1520-5215. ; 108:42, s. 9226-9232
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Tidskriftsartikel (refereegranskat)abstract
- A transformed Hamiltonian for a triatomic molecule in Radau coordinates is employed for time-dependent wave packet calculations. The first photoelectron band of the OClO molecule is calculated by propagating the wave packet on a three-dimensional Fourier grid with the split operator method. To find the intial wave function, we first calculate the few lowest one-dimensional eigenfunctions along each Radau coordinate by the Fourier grid Hamiltonian method. The direct product of these eigenfunctions is then used as basis set for obtaining the initial ground state vibrational wave function, which in this way is expressed directly on the three-dimensional Fourier grid. Consistent with the results of a previous two-dimensional study, we find that the asymmetric stretch plays little role in the photoionization process. An improved equilibrium geometry for the potential energy surface function of the ground electronic state of OClO+ was found by iteratively comparing with the experimental photoelectron spectrum. Using the approach employed here, it is easy to treat a timed-dependent Hamiltonian.
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