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101.
Mary McPartlin 《Polyhedron》1984,3(12):1321-1328
The recently developed electron-counting rules for condensed polyhedral metal carbonyl clusters have been utilised to develop a systematic approach for enumerating the structural alternatives for metal cluster compounds which are isoelectronic. The more usual cluster degradation and aggregation processes are represented in a matrix form which relates the change in electron count to the number of new bonds formed (or broken). The matrices for cluster degradation and aggregation are represented in a complementary fashion so that the search for isoelectronic clusters greatly simplified. The utility of the approach is illustrated by reference to some recent examples from metal carbonyl cluster chemistry. 相似文献
102.
C. Mioskowski A. Solladie-Cavallo G. Solladie 《Journal of organometallic chemistry》1978,149(3):C63-C65
Attachment of a Cr(CO)3 moiety to one of the aromatic rings in rigid diaryl ketones of very low prochirality followed by addition of a chiral and optically pure reagent leads to satisfactory asymmetric induction ~40%. Asymmetric induction is smaller in the case of acyclic systems. 相似文献
103.
The kinetics of the reaction between organocobaloximes, RCo(DH)2H2O, and iodine have been investigated. They reveal the participation of an RCo(DH)2H2O · I2 intermediate which undergoes intramolecular transalkylation and acts as an electrophile towards a second organocobaloxime molecule. The trend in reactivity as the R group is varied is discussed. 相似文献
104.
Pentacoordinate complex cations of the general formula [(C6F5)2SbL3]3+ stabilized as solid salts in combination with tetraphenylborate (BPh4), tetrafluorobroate (BF4) anions, where L=DMSO, Ph3AsO, PyO, DMF, α-, β- and γ-picoline have been isolated. The newly formed complexes were characterized by elemental analysis, molar conductance measurements, solid-state IR and and NMR. From these results, a five-fold coordination around antimony was required. 相似文献
105.
L. S. Zakharov G. N. Molchanova T. M. Shcherbina P. V. Petrovskii M. I. Kabachnik 《Russian Chemical Bulletin》1998,47(9):1718-1724
A number of trialkylsilylmethyl diphenyl phosphates MeRR′SiCH2OP(O)(OPh)2 (1a-e: R=Et (a), Pr (b), CF3CH2CH2 (c, e), Me3SiCH2 (d); R′=Me (a-d), Et (e)) were synthesized and their thermal rearrangement, of the 1,2-shift type, was studied. The rearrangement consists of the
migration of an alkyl group from Si atom to the methylene carbon atom and gives the corresponding silyl esters. The rate of
the rearrangement was found to increase in the order1d<1b<1a<1 (R=R′=Me)<1c corresponding to the enhancement of the total inductive effect (−I) of the substituents at the Si atom. The relative migration ability of the substituents at the Si atom, determined by GC/MS
analysis of the disiloxane fraction resulting from hydrolysis of pyrolyzed phosphates1a-e, increases in the order R=Pr<Et<CF3CH2CH2<Me≪Me3SiCH2, which differs substantially from the order in which the rate of the rearrangement of phosphates1a-d changes. The electronegativity of the migrating group affects noticeably the relative ability to migrate.
For Part 4, see Ref. 1.
Deceased.
Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 9, pp. 1767–1772, September, 1998. 相似文献
106.
Molecular mechanics calculations on cycloheptadiene indicate that the molecule has a structure which undergoes a wide pseudorotational motion between two C1 forms, and a C1 form, and this structure is in equilibrium with the C2 form. It is shown that this equilibrium mixture is consistent with all of the available experimental data. 相似文献
107.
A spectrophotometric study on a direct picric acid reaction for creatinine in severely jaundiced serums is described. A problem appears to be caused by the oxidation of bilirubin which minimizes rising absorbance when using continuous measurement. Simple examples of interferences with the kinetic mode are shown along with the hitherto unreported interference of the drug, Cephalothin, which also undergoes a picric acid reaction. A procedure in which a delta absorbance is obtained after decolorization of the Jaffé complex by acidification is shown as one available means for obviating the bilirubin effect. However, the theory that Jaffé-reactive interferences do not decolorize with the same acid treatment is not totally applicable when the drug, Cephalothin, is present. 相似文献
108.
Michel Spiesser Robert P. Gruska S.N. Subbarao Carlos A. Castro Aaron Wold 《Journal of solid state chemistry》1978,26(2):111-114
Crystals of antimony-doped In2Se3 were grown by the Bridgeman method. This compound, whose composition is In1.8Sb0.2Se3, appears to be isostructural with In1.9As0.1Se3. The refined unit cell parameters are a = 3.97(1), c = 18.87(1) Å. Orthorhombic crystals of InSbSe3 were grown from an isothermal melt. The refined unit cell parameters are a = 9.43(1), b = 14.02(5), and c = 3.96(1) Å. These parameters agree with those determined for α-InSbSe3 by other studies. The observed densities measured by a hydrostatic technique are 5.98(3) g/cm3 for In1.8Sb0.2Se3 and 6.07(2) g/cm3 for InSbSe3. The room temperature dc resistivity for In1.8Sb0.2Se3 has been found to be 4.4 × 104 Ω-cm, whereas that of InSbSe3 has been found to be 15.2(1) Ω-cm. A resistivity versus temperature study has beenn carried out for InSbSe3 between 230 and 400°K. Optical studies indicate that In1.8Sb0.2Se3 is an n-type semiconductor with a band gap of 1.1 eV and InSbSe3 is a p-type semiconductor with a band gap of 0.92 eV. 相似文献
109.
Mohamed El Guendouzi Abderrahim Dinane Abdelfetah Mounir 《Journal of solution chemistry》2002,31(2):119-129
The mixed aqueous electrolyte system of ammonium and lithium chlorides has been studied by the hygrometric method at 25°C. The relative humidities of this system are measured at total molalities from 0.3 to 6 mol-kg– 1 for different ionic-strength fractions y of NH4Cl with y = 0.33, 0.50, and 0.67. The data obtained allow the deduction of new water activities and osmotic coefficients. The experimental results are compared with the predictions of the ECA (extended composed additivity) law proposed in our previous work. The Zdanovskii–Stokes–Robinson (ZSR), the Robinson–Stokes (RS), Reilly–Wood–Robinson (RWR), the Pitzer, and the Lietzke–Stoughton (LS II) models are also compared with our results. Predictions made using these models are, in general, consistent with our results. From these measurements, new Pitzer mixing ionic parameters are determined and used to predict the solute activity coefficients in the mixture for different ionic-strength fractions. 相似文献
110.
Boris Pejin Kristina Tešanović Dragica Jakovljević Sonja Kaišarević Filip Šibul Milena Rašeta 《Natural product research》2019,33(5):750-754
The polysaccharide (PSH) extracts from the edible mushroom species Coprinus comatus and Coprinellus truncorum were screened in liquid for their acetylcholinesterase inhibitory (AChE) activity. Both extracts were found to display inhibition of the aforementioned enzyme reaching similar IC50 values of 0.62 ± 0.07 and 0.61 ± 0.03 mg/mL, respectively. According to the means of FTIR spectroscopy, these PSH extracts mostly contained β-glucans. However, the presence of some proteins and polyphenolics as minor ingredients were also detected. Compared with existing literature data for anti-AChE activity of the sugar samples, the findings within this study may be treated as a profound bioactivity. Consequently, this study puts some light on the possible use of the screened macrofungi in the palliative treatment of Alzheimer’s disease. 相似文献