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101.
Andrea Marchi Roberto Rossi Adriano Duatti Gian Luigi Zucchini Luciano Magon 《Transition Metal Chemistry》1986,11(5):164-166
Summary The complex [Tc(PPh3)2(CO)3Cl] reacts with the lithium salt of amido-carboxylato- and thiazolato-derivatives to give the new complexes (Ar= C6H4Me-p or C6H4OMe-p), [Tc(PPh3)2(CO)2(amt1,2)] [amt1=anion of 2-(methylamino)thiazole; amt2=anion of 2-4-methoxyphenylamino(thiazole)] and [Tc(PPh3)2(CO)2- (R = Ph2CH, PhCH2 or CCl3). The compounds have been characterized by elemental analysis, and i.r. and1H n.m.r. spectra. 相似文献
102.
von Lilienfeld OA Tavernelli I Rothlisberger U Sebastiani D 《The Journal of chemical physics》2005,122(1):14113
In plane wave based electronic structure calculations the interaction of core and valence electrons is usually represented by atomic effective core potentials. They are constructed in such a way that the shape of the atomic valence orbitals outside a certain core radius is reproduced correctly with respect to the corresponding all-electron calculations. Here we present a method which, in conjunction with density functional perturbation theory, allows to optimize effective core potentials in order to reproduce ground-state molecular properties from arbitrarily accurate reference calculations within standard density functional calculations. We demonstrate the wide range of possible applications in theoretical chemistry of such optimized effective core potentials (OECPs) by means of two examples. We first use OECPs to tackle the link atom problem in quantum mechanics/molecular mechanics (QM/MM) schemes proposing a fully automatized procedure for the design of link OECPs, which are designed in such a way that they minimally perturb the electronic structure in the QM region. In the second application, we use OECPs in two sample molecules (water and acetic acid) such as to reproduce electronic densities and derived molecular properties of hybrid (B3LYP) quality within general gradient approximated (BLYP) density functional calculations. 相似文献
103.
Marvelli L Mantovani N Marchi A Rossi R Brugnati M Peruzzini M Barbaro P de los Rios I Bertolasi V 《Dalton transactions (Cambridge, England : 2003)》2004,(5):713-722
A family of new Fischer-type rhenium(III) benzoyldiazenido-2-oxacyclocarbenes of formula [(ReCl2[eta1-N2C(O)Ph][=C(CH2)nCH(R)O](PPh3)2][n = 2, R = H (2), R = Me (3); n = 3, R = H (4), R = Me (5)] have been prepared by reaction of [ReCl2[eta2-N2C(Ph)O](PPh3)2] (1) with omega-alkynols, such as 3-butyn-1-ol, 4-pentyn-1-ol, 4-pentyn-2-ol, 5-hexyn-2-ol in refluxing THF. The correct formulation of the carbene derivatives 2-5 has been unambiguously determined in solution by NMR analysis and confirmed for compounds 2-4 by X-ray diffraction methods in the solid state. All complexes are octahedral with the benzoyldiazenido ligand, Re[N2C(O)Ph], adopting a "single bent" conformation. The coordination basal plane is completed by an oxacyclocarbene ligand and two chlorine atoms. Two triphenylphosphines in trans positions with respect to each other complete the octahedral geometry around rhenium. The reactivity of 1 towards different alkynes and alkenes including propargyl- and allylamine has been also studied. With propargyl amine, monosubstituted or bisubstituted complexes, [(ReCl2[eta1-N2C(O)Ph][eta1-NH2CH2C triple bond CH]n(PPh3)(3-n)][n= 1 (6); n = 2 (7)], have been isolated depending on the reaction conditions. In contrast, the reaction with allylamine gave only the disubstituted complex [(ReCl2[eta1-N2C(O)Ph][eta1-NH2CH2CH=CH2]2(PPh3)] (8). The molecular structure of the monosubstituted adduct has been confirmed by X-ray analysis in the solid state. 相似文献
104.
G. De Marchi F. Caccavale F. Gonella G. Mattei P. Mazzoldi G. Battaglin A. Quaranta 《Applied Physics A: Materials Science & Processing》1996,63(4):403-407
Light waveguides containing silver, introduced by ion-exchange process in soda-lime glass, has been annealed in hydrogen atmosphere at temperatures in the 120–250°C range. Annealings cause a near-surface precipitation of metallic silver to form nanometer-size clusters with good uniformity in size and spatial distribution. Hydrogen permeation and ion-exchange between hydrogen and sodium (which remains in the glass matrix after silver-for-sodium exchange) are steps of the annealing process. A further step is the diffusion of silver ions towards the surface, and its eventual precipitation, with an activation energy close to that measured for silver-sodium interdiffusion in glasses of comparable composition. 相似文献
105.
106.
A simple and reliable FIA-potentiometric system for rapid assays of chloride in certain food samples is described and evaluated. The system is constituted by an aquarium air pump to propel the carrier solution, a manually operated injector, a homemade dialysis flow cell, a solid-state chloride detector (Ag/AgCl), a reference electrode and a multimeter connected to a microcomputer for data acquisition. The dialysis unit enables direct analysis of liquid food samples without any other previous treatment. The principal novelties are the precision (R.S.D. of 1.2% for whole milk) and rapidity (90 determinations/h) of FIA measurements near and below the lower end of the linear (Nernstian) response region of the chloride ion-selective electrode (ISE), with an estimated detection limit (3 s) of 0.4 mg L−1 Cl− in the sample injected in donor stream. Data of peak potential versus sample chloride concentration (donor stream) was accurately fitted with a quadratic polynomial over the range between 4 and 1000 mg L−1 (r2 = 0.9999) and used as a calibration curve. The method was applied to the determination of chloride in milk and in coconut water samples. The validation of the results was done by comparison with a NIST reference material (milk) or by capillary electrophoresis (coconut water). For all analysis, no significant difference at a 95% confidence level was observed. 相似文献
108.
109.
Enrico Marchi 《Meccanica》1966,1(3-4):34-36
Summary The stationary surface waves in a quasi-uniform flow approaching the critical conditions are shown to be possible only around a basic normal depth greater than critical.The demonstration is based on the second order equation of steady two-dimensional flow (cnoidal waves equation). 相似文献
110.
Ezio Marchi 《Probability Theory and Related Fields》1969,12(3):223-230
Summary A natural extension of the minimax theorem for cooperative games is considered.This work was prepared at the Econometric Research Program of Princeton University and it has been partially supported by the Office of Naval Research under contract No. 1958 (16). 相似文献