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11.
Montilla F Galindo A Rosa V Aviles T 《Dalton transactions (Cambridge, England : 2003)》2004,(16):2588-2592
The donor strengths of the following triarylphosphine ligands P(Ar)(2)(Ar')(Ar = Ar'= 4-Me(3)SiC(6)H(4), 1b; 4-Me(3)CC(6)H(4), 1d; 4-F(3)CC(6)H(4), 1e; Ar = C(6)H(5), Ar'= 4-Me(3)SiC(6)H(4), 1c) have been evaluated experimentally and theoretically. The measurements of the J(P-Se) coupling constants of the corresponding synthesised selenides Se=P(Ar)(2)(Ar'), 2b,c and the DFT calculation of the energies of the phosphine lone-pair (HOMO) reveal insignificant influence on the electronic properties of the substituted phosphines when the trimethylsilyl group is attached to the aryl ring, in marked contrast to the strong electronic effect of the trifluoromethyl group. These triarylphosphine ligands P(Ar)(2)(Ar') reacted with (eta5-C(5)H(5))Co(CO)(2), (eta5-C(5)H(5))Co(CO)I(2) or PdCl(2) to yield the new compounds (eta5-C(5)H(5))Co(CO)[P(Ar)(2)(Ar')], 3b,d; (eta5-C(5)H(5))CoI(2)[P(Ar)(2)(Ar')], 4b-e; and PdCl(2)[P(Ar)(2)(Ar')](2), 5b,c respectively. These complexes have been characterized and their spectroscopic properties compared with those reported for the known triphenylphosphine complexes. Again, the contrast of the (31)P NMR and (13)C NMR chemical shifts or C-O or M-Cl stretching frequencies, when applied, does not show an important electronic effect on the metal complex of the trimethylsilyl substituted phosphines with respect to P(C(6)H(5))(3) derivatives. Solubility measurements of complexes 3a and 3b in scCO(2) were performed. We conclude that Me(3)Si groups on the triarylphosphine improve the solubility of the corresponding metal complex in scCO(2). 相似文献
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Ewa T. Stepkowska M. A. Aviles J. M. Blanes J. L. Perez-Rodriguez 《Journal of Thermal Analysis and Calorimetry》2007,87(1):189-198
The low temperature
of decomposition of some calcium carbonates and the bending of the TG curves
of hydrated cement between 500 and 800°C suggested the presence of some
complex compound(s), which needed complementary investigation (XRD, TG). Stepwise
transformation of portlandite (and/or lime) into calcium carbonate, with intermediate
steps of calcium carbonate hydroxide hydrates (CCH-1 to CCH-5), was indicated
by the previous study of two OPC.
This was checked here on four
cements ground for t
g=15,
20, 25 and 30 min and hydrated either in water vapour, successively at RH=1.0,
0.95 and 0.5 for 2 weeks each (WR1, WR2 and WR3, respectively) or as mortars
in liquid water (1m), followed by WR as above. The d[001] spacing of portlandite
was confirmed to vary: here between the lowest and the highest standard values.
The diffractograms of n=32 different samples
were analyzed for presence of standard CCH peaks, generally slightly displaced.
These were: CCH-1 [Ca3(CO3)2(OH)2]: N=11 peaks, of three different d[hkl] spacings, CCH-2 [Ca6(CO2.65)2(OH657)7(H2O)2]: N=10 for two d[hkl], CCH-3 [Ca3(CO3)2(OH)2·1.5H2O]: N=14 for five d[hkl], CCH-4,
ikaite [CaCO3(H2O)6]: N=13 for six d[hkl], CCH-5[CaCO3(H2O)]: N=15 for five d[hkl]. Thus the most probable is the presence of the
last three. The stepwise transformation of Ca(OH)2
into CaCO3 was confirmed: 相似文献
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Patricio Aviles 《Communications in Mathematical Physics》1987,108(2):177-192
We study the local behavior of solutions of some nonlinear elliptic equations. These equations are of interest in differential geometry and mathematical physics. 相似文献
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Horn A Møllendal H Demaison J Petitprez D Aviles Moreno JR Benidar A Guillemin JC 《The journal of physical chemistry. A》2005,109(17):3822-3829
The structural and conformational properties of allylgermane have been investigated using Stark and Fourier transform microwave spectroscopies, infrared spectroscopy, and high-level quantum chemical calculations. The parent species H2C=CHCH2GeH3 was investigated by microwave spectroscopy and infrared spectroscopy, while three deuterated species, namely, H2C=CDCH2GeH3, H2C=CHCHDGeH3, and H2C=CHCH2GeD3, were studied only by infrared spectroscopy. The microwave spectra of the ground vibrational state as well as of the first excited state of the torsion vibration around the sp2-sp3 carbon-carbon bond were assigned for the 70Ge, 72Ge, and 74Ge isotopomers of one conformer. This rotamer has an anticlinal arrangement for the C=C-C-Ge chain of atoms. The infrared spectrum of the gas in the 500-4000 cm(-1) range has been assigned. No evidence of additional rotameric forms other than anticlinal was seen in the microwave and infrared spectra. Several different high-level ab initio and density functional theory calculations have been performed. These calculations indicate that a less stable form, having a synperiplanar conformation of the C=C-C-Ge link of atoms, may coexist with the anticlinal form. The energy differences between the synperiplanar and anticlinal forms were calculated to be 5.6-9.2 kJ/mol depending on the computational procedure. The best approximation of the equilibrium structure of the anticlinal rotamer was found in the MP2/aug-cc-pVTZ calculations. The barrier to internal rotation of the germyl group was found to be 6.561(17) kJ/mol, from measurements of the splitting of microwave transitions caused by tunneling of the germyl group through its threefold barrier. 相似文献
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Yin J Aviles P Lee W Ly C Floriano P Ignacio M Faircloth G 《Rapid communications in mass spectrometry : RCM》2003,17(16):1909-1914
A rapid and sensitive liquid chromatography/tandem mass spectrometry (LC/MS/MS) assay was developed and validated to quantify a novel marine-derived depsipeptide, Aplidin, in human plasma. The method was validated to demonstrate the specificity, recovery, limit of quantitation (LOQ), accuracy, and precision of measurements. The calibration range for Aplidin was established using Aplidin standards from 0.05-50 ng/mL in blank human plasma. The multiple reaction monitoring, based on the transition m/z 1110.7 --> 295.3, was specific for Aplidin, and that based on the transition m/z 1112.6 --> 297.3 was specific for didemnin B (the internal standard); no endogenous materials interfered with the analysis of Aplidin and didemnin B from blank human plasma. The assay was linear over the concentration range 0.05-50.0 ng/mL. The correlation coefficients for the calibration curves ranged from 0.9979 to 0.9999. The mean intra- and interday accuracies for all calibration standards (n = 12) ranged from 97 to 106% (=6% bias), and the mean interday precision for all calibration standards was less than 8.3%. The mean intra- and interday assay accuracy for all quality control replicates (n = 12), determined at each QC level throughout the validated runs, remained below 12 and 7%, respectively. The mean intra- and interday assay precision was less than 13.1 and 10.7% for all QC levels, respectively. The assay is currently used to measure Aplidin plasma concentrations to support clinical trials. 相似文献
20.
Cuisset A Aviles Moreno JR Huet TR Petitprez D Demaison J Crassous J 《The journal of physical chemistry. A》2005,109(25):5708-5716
The rotational spectrum of chlorofluoroiodomethane (CHClFI) has been investigated. Because its rotational spectrum is extremely crowded, extensive ab initio calculations were first performed in order to predict the molecular parameters. The low J transitions were measured using a pulsed-molecular-beam Fourier transform spectrometer, and the millimeter-wave spectrum was measured to determine accurate centrifugal distortion constants. Because of the high resolution of the experimental techniques, the analysis yielded accurate rotational constants, centrifugal distortion corrections, and the complete quadrupole coupling tensors for the iodine and chlorine nuclei, as well as the contribution of iodine to the spin-rotation interaction. These molecular parameters were determined for the two isotopologs CH35ClFI and CH37ClFI. They reproduce the observed transitions within the experimental accuracy. Moreover, the ab initio calculations have provided a precise equilibrium molecular structure. Furthermore, the ab initio molecular parameters are found in good agreement with the corresponding experimental values. 相似文献