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La herencia de la filosof??a cl??sica y su vigencia en la actualidad

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Basis set superposition error-counterpoise corrected potential energy surfaces : application to hydrogen peroxide ... X (X=F-, Cl-, Br-, Li+, Na+) complexes

Møller-Plesset (MP2) and Becke-3-Lee-Yang-Parr (B3LYP) calculations have been used to compare the geometrical parameters, hydrogen-bonding properties, vibrational frequencies and relative energies for several X- and X+ hydrogen peroxide complexes. The geometries and interaction energies were corrected for the basis set superposition error (BSSE) in all the complexes (1-5), using the full counterpoise method, yielding small BSSE values for the 6-311 + G(3df,2p) basis set used. The interaction energies calculated ranged from medium to strong hydrogen-bonding systems (1-3) and strong electrostatic interactions (4 and 5). The molecular interactions have been characterized using the atoms in molecules theory (AIM), and by the analysis of the vibrational frequencies. The minima on the BSSE-counterpoise corrected potential-energy surface (PES) have been determined as described by S. Simón, M. Duran, and J. J. Dannenberg, and the results were compared with the uncorrected PES

Laboratory kinetic studies of the reactions of Cl atoms with species of biogenic origin: δ3-Carene, isoprene, methacrolein and methyl vinyl ketone

The rate coefficients for the reaction between atomic chlorine and a number of naturally occurring species have been measured at ambient temperature and atmospheric pressure using the relative rate technique. The values obtained were (4.0 ± 0.8) × 10-10, (2.1 ± 0.5) × 10-10, (3.2 ± 0.5) × 10-10, and (4.9 ± 0.5) × 10-10 cm3 molecule-1 s-1, for reactions with isoprene, methyl vinyl ketone, methacrolein and δ3-carene, respectively. The value obtained for isoprene compares favourably with previously reported values. No values have been reported to date for the rate constants of the other reactions.

Analytical potentials for triatomic molecules from spectroscopic data V. Application to HOX (X=F, Cl, Br, I)

Analytical potential energy functions are reported for HOX (X=F, Cl, Br, I). The surface for HOF predicts two metastable minima as well as the equilibrium configuration. These correspond to HFO (bent) and OHF (linear). Ab initio calculations performed for the HOF surface confirm these predictions. Comparisons are drawn between the two sets of results, and a vibrational analysis is undertaken for the hydrogen bonded OHF species. For HOCl, one further minimum is predicted, corresponding to HClO (bent), the parameters for which compare favourably with those reported from ab initio studies. In contrast, only the equilibrium configurations are predicted to be stable for HOBr and HOI.

The vibrational spectra of natural and perdeuterated monochlorogallane, H2Ga([mu]-Cl)2GaH2, and an empirical harmonic potential function

The infrared and Raman spectra of monochlorogallane and its fully deuterated isotopomer are recorded and assigned on the basis of the dimeric structures. H2Ga(μ-Cl)2GaH2 and D2Ga(μ-Cl)2GaD2, conforming to D2 symmetry. The observed frequencies are corrected for anharmonicity and fitted to a potential function in which 19 of the 33 independent force constants are refined.

Argon predissociation spectroscopy of the OH-center dot H2O and Cl-center dot H2O complexes in the 1000-1900 cm(-1) region: Intramolecular bending transitions and the search for the shared-proton fundamental in the hydroxide monohydrate

We present argon predissociation vibrational spectra of the OH-.H2O and Cl-.H2O complexes in the 1000-1900 cm(-1) energy range, far below the OH stretching region reported in previous studies. This extension allows us to explore the fundamental transitions of the intramolecular bending vibrations associated with the water molecule, as well as that of the shared proton inferred from previous assignments of overtones in the higher energy region. Although the water bending fundamental in the Cl-.H2O spectrum is in very good agreement with expectations, the OH-.H2O spectrum is quite different than anticipated, being dominated by a strong feature at 1090 cm(-1). New full-diniensionality calculations of the OH-.H2O vibrational level structure using diffusion Monte Carlo and the VSCF/CI methods indicate this band arises from excitation of the shared proton.

trans-[Ru-III(N-N)(2)Cl-2](+) species, where N-N is bis(3,5-dimethylpyrazol-1-yl)methane

Using bis(3,5-dimethylpyrazol-1-yl)methane as an N-N donor ligand, a trans-[Ru-III(N-N)(2)Cl-2](+) core has been isolated from the direct reaction of the ligand with RuCl3 center dot xH(2)O and characterized structurally for the. first time. The core displays a rhombic EPR spectrum and a quasireversible Ru(II/III) couple with an E-1/2 of -0.34 V versus NHE. (C) 2008 Elsevier B.V. All rights reserved.

Soluble redox-active polymetallic chains [{Ru-0(CO)(L)(bpy)}(m)](n) (bpy=2,2 '-bipyridine, L = PrCN, Cl-; m=0,-1): electrosynthesis and characterization

Electrochemical and spectroelectrochemical techniques were employed to study in detail the formation and so far unreported spectroscopic properties of soluble electroactive molecular chains with nonbridged metal-metal backbones, namely, [{Ru-0(CO)(PrCN)(bpy)}(m)](n) (m = 0, -1) and [{Ru-0(CO)(bpy)Cl}(m)](n) (m = -1, -2; bpy = 2,2'-bipyridine). The precursors cis-(Cl)-[Ru-II(CO)(MeCN)(bpy)Cl-2] (in PrCN) and mer-[Ru-II(CO)(bpy)Cl-3](-) (in tetrahydrofuran (THF) and PrCN) undergo one-electron reductions to reactive radicals [Ru-II(CO)(MeCN)(bpy(center dot-))Cl-2](-) and [Ru-II(CO)(bpy(center dot-))Cl-3](2-), respectively. Both [bpy(center dot-)]-containing species readily electropolymerize on concomitant dissociation of two chloride ligands and consumption of a second electron. Along this path, mer-to-fac isomerization of the bpy-reduced trichlorido complex (supported by density functional theory calculations) and a concentration-dependent oligomerization process contribute to the complex reactivity pattern. In situ spectroelectrochemistry (IR, UV/vis a has revealed that the charged polymer [{Ru-0(CO)(bpy)Cl}(-)](n) is stable in THF, but in PrCN it converts readily to [Ru-0(CO)(PrCN)(bpy)](n). An excess of chloride ions retards this substitution at low temperatures. Both polymetallic chains are completely soluble in the electrolyte solution and can be reduced reversibly to the corresponding [bpy(center dot-)]-containing species.

Intercalation of diiodine molecules in cis-Ru(bpy)(2)Cl-2

Reaction of diiodine with cis-Ru(bpy)(2)Cl-2 in methanol at room temperature yields a thermally stable intercalate cis-Ru(bpy)(2)Cl-2 center dot 1.7I(2) (1) which has been characterised by X-ray crystallography. Iodine is leeched from 1 as it reacts with acetone at room temperature. (C) 2005 Elsevier B.V. All rights reserved.