The reaction of diarylzinc compounds with silver salts : Synthesis and characterization of arylsilver(I) compounds

The reaction of diarylzinc compounds with silver(I) salts is an excellent method of preparing stable arylsilver compounds in quantitative yields. These compounds have been characterized by IR and ¹H and ¹³C NMR spectroscopy Cryoscopy in benzene shows phenylsilver to be polymeric, and the methyl-substituted phenylsilver compounds to be trimers. All the compounds appear to be associated via aryl groups bridging between two silver atoms. As in the case of the corresponding copper compounds, the data point to the existence of rotation of these aryl groups around the C¹C⁴ axis. C¹C⁴ axis.     

Esr studies on the reactive character of the radical anions,so−2, so−3 and so−4 in aqueous solution

The reactive characteristics of the oxy anion radicals of sulphur, SO^?₂, SO^?₃ and SO^?₄ were investigated by use of the rapid-mixing flow technique coupled with electron spin resonance (ESR) which can detect the radicals having a lifetime of 5–100 msec. The SO^?₂ reduced the aromatic nitro compounds to the corresponding anion radicals, but did not abstract the hydrogen from the saturated compounds nor add to the unsaturated compounds. The SO^?₃ could add to the compounds having CC bond, but did not abstract the hydrogen from the saturated compounds nor reduce the aromatic nitro compounds. The SO^?₄ could abstract the hydrogen from the saturated compounds and also add to the unsaturated compounds having CC bond, but did not reduce the aromatic nitro compounds. These differences of the reactivity towards the organic substrates were discussed on the basis of the difference in the distribution of the unpaired electron density of each radical anion.     

13C and 119Sn NMR spectra of Di-n-butyltin(IV) compounds

The ¹³C and ¹¹⁹Sn NMR spectra of a set of di-n-butyltin(IV) compounds and their complexes in coordinating and non-coordinating solvents have been studied. The results have shown that it is possible to describe semiquantitatively the shape of coordination polyhedra of these compounds from analysis of their δ(¹¹⁹Sn) and ¹J(¹¹⁹Sn-¹³C) parameters. The values of δ(¹¹⁹Sn) define the regions with different coordination numbers of the central tin atom, so that four-coordinate compounds have δ(¹¹⁹Sn) ranging from about + 200 to −60 ppm, five-coordinate compounds, −90 to −190 ppm, and six-coordinate compounds, −210 to −400 ppm. The values of ¹J(¹¹⁹Sn-¹³C) were used for the calculation of the CSnC angle in the coordination polyhedron of individual compounds.     

Synthesis and 1H, 13C and 15N NMR characterisation of substituted Pyrazolo[4,3-c]quinolines and related compounds

A wide range of novel and known alkyl substituted pyrazolo[4,3-c]quinolines and related compounds were synthesized. Some of these compounds can undergo tautomerism and differences have been noted in the structural assignments already published. For each of these compounds, a complete assignment was made using ¹H, ¹³C and ¹⁵N one- and two-dimensional NMR measurements, including NOESY, COSY, ¹H-¹³C HSQC and ¹H-¹³C HMBC. ¹H-¹⁵N HMBC NMR has proved crucial in determining the relevant tautomeric and protonated state of the compounds.     

Order—disorder in compounds LiMe2+VO4

The crystallographic order between the Li⁺ and Me²⁺ ions in some compounds LiMeVO₄ (Me = Mg, Co, Ni, Cu, Zn) has been investigated by vibrational spectroscopy. The Li⁺ and Me²⁺ ions are disordered in the cobalt and nickel compounds and ordered in the copper and magnesium compounds.     

Analysis of Corrosion Products Formed on Cu-Ni Alloys Immersed in Sea Water

Abstract

A method was developed for separation and analysis of corrosion products formed on the surface of Cu-Ni alloys immersed in sea water polluted by sulphide ions. This method is based on the selective dissolution of oxidation compounds by suitable solvents dissolving the metal matrix only to a negligeable extent.

The following solvents were used: 1) methanol to dissolve Na⁺, Cu²⁺, Ni²⁺ chlorides and sulphates; 2) glycine to dissolve bivalent metal compounds - Cu²⁺, Ni²⁺ oxides, sulphides, oxysulphates, oxychlorides and oxycarbonates; 3) ammonia solution to dissolve Cu⁺ compounds (i.e. Cu₂O and CuCl); 4) potassium cyanide to dissolve CU⁺ sulphides.

Reasonable agreement between chemical and X-Ray analysis results was observed only for copper compounds, since nickel and iron compounds could not tie observed by X-Ray diffraction. The results of Auger and chemical analyses better agree with each other, yet no Fe compounds could be detected. This is to be attributed to the non-homogeneous corrosion layer which notably contains Fe compounds in the innermost region at a depth where Auger spectroscopy is unable to detect them, whereas their detection is possible by chemical analysis, since it is a bulk analysis.     

Density Functional Theoretical Study of Polynitrogen Compounds N5+Y− (Y=B(CF3)4, BF4, PF6 and B(N3)4)

The structures and the stabilities of polynitrogen compounds N₅⁺Y^? [Y=B(CF₃)₄, BF₄, PF₆, and B(N₃)₄], as the potential high energy density compounds, have been investigated at the B3LYP/6‐31G(d,p) and B3LYP/6‐311+G(d,p) levels. On the basis of our geometry optimization calculations, the structural properties of the N₅⁺Y^? compounds are discussed, and it is found that the combination of the N₅⁺ cation and the Y^? anions leads to distortion of the structures of the Y^? anions. Based on the TS calculations for the N₂‐loss dissociations of the N₅⁺Y^? compounds, the stabilities of these compounds are discussed, and the following conclusion can be drawn that among the four compounds, N₅⁺B(CF₃)₄^? is the most stable one and N₅⁺B(N₃)₄^? is the most unstable, and the relative stability of these compounds is always consistent using different basis sets. From these discussions, it is revealed that there are close correlations between the stuctrual distortions of the Y^? anions and the stabilities of the N₅⁺Y^? compounds, and between the nitrogen content in the compounds and the stabilities of the N₅⁺Y^? compounds.     

Synthesis,structural characterization,and anion interactions of new triazole-linked urea derivative fully substituted cyclotriphosphazene compounds

Three novel fully substituted urea derivative cyclotriphosphazene compounds 5–7 were synthesized by alkyne-azide 1,3-dipolar cycloaddition reaction of propargyl substituted ureas 2–4 with hexaazide substituted cyclotriphosphazene 1 in the presence of Cu(I) catalyst. All compounds were characterized with spectroscopic techniques such as FT-IR, ¹H, ¹³C, and ³¹P nuclear magnetic resonance and mass spectroscopy. Also, the usefulness of compounds 5–7 as anion carriers was investigated by ¹H NMR spectroscopy. For this purpose, ¹H NMR spectra of compounds 5–7 were recorded in the presence of tetrabutylammonium fluoride in DMSO-d₆. It was determined, that the urea protons in the compounds interact with fluoride.     

Die Bildung von Jodkationen durch Solvolyse von N-Jodverbindungen in starken Protonsäuren

N-iodo compounds dissolve in strong proton acids forming brown (conc. H₂SO₄) or blue to bluish green (oleum, FSO₃H) solutions. Their colour and UV-VIS-spectra show the presence of J₃ ⁺-resp. J₂ ⁺-ions, which can be explained by the interaction of the N-iodo compounds with solvent molecules and disproportionation of thereby emerging J⁺-ions. As a result of this solvolytic behaviour, in contrast to the corresponding N-bromo compounds, no differences in the halogenating activity of the various N-iodo compounds against deactivated aromatic compounds are observed.     

Optimizing the sensitivity and radiological properties of the PRESAGE® dosimeter using metal compounds

The aim of this study is to investigate the radiation-modifying effects of incorporating commercially available bismuth-, tin- and zinc-based compounds in the composition of the PRESAGE^® dosimeter, and the feasibility of employing such compounds for radiation dose enhancement. Furthermore, we demonstrate that metal compounds can be included in the formulation to yield water-equivalent PRESAGE^® dosimeters with enhanced dose response. Various concentrations of the metal compounds were added to a newly developed PRESAGE^® formulation and the resulting dosimeters were irradiated with 100 kV and 6 MV photon beams. A comparison between sensitivity and radiological properties of the PRESAGE^® dosimeters with and without the addition of metal compounds was carried out. Optical density changes of the dosimeters before and after irradiation were measured using a spectrophotometer. In general, when metal compounds were incorporated in the composition of the PRESAGE^® dosimeter, the sensitivity of the dosimeters to radiation dose increased depending on the type and concentration of the metal compound, with the bismuth compound showing the highest dose enhancement factor. In addition, these metal compounds were also shown to improve the retention of the post-response absorption value of the PRESAGE^® dosimeter over a period of 2 weeks. Thus, incorporating 1–3 mM (ca. 0.2 wt%) of any of the three investigated metal compounds in the composition of the PRESAGE^® dosimeter is found to be an efficient way to enhance the sensitivity of the dosimeter to radiation dose and stabilize its post-response for longer times. Furthermore, the addition of small amounts of the metal compounds also accelerates the polymerization of the PRESAGE^® dosimeter precursors, significantly reducing the fabrication time. Finally, a novel water-equivalent PRESAGE^® dosimeter formula optimized with metal compounds is proposed for clinical use in both kilovoltage and megavoltage radiotherapy dosimetry.     

Effect of six triorganotin(IV) compounds on nitrification and ammonification in soil

The effects of six triorganotin(IV) compounds and of Thiram on nitrification and ammonification in soil were investigated. Low concentrations of up to 50 μg g^?1 of the triorganotin(IV) compounds enhanced nitrate-nitrogen (NO₃^?-N) production in soil. Except for diphenylbutyltin bromide, which inhibited nitrification at 250 μg g^?1, the other triorganotin(IV) compounds were inhibitory at concentrations of 100 μg g^?1 to less than 250 μg g^?1. At 10 μg g^?1, only triphenyltin acetate was less inhibitory towards nitrification compared with Thiram. At 250 μg g^?1, Thiram exerted a strongly persistent inhibitory effect towards nitrification. The NO₃^?-N level recorded 28 days after application was only 0.10 μg g^?1 soil. With the triorganotin compounds NO₃^?-N levels of 7.05–12.06 μg g^?1 soil were recorded 28 days following their application. The deleterious effects of the triorganotin(IV) compounds were less persistent and recovery of nitrification was evident seven days after application. Low concentrations of Thiram and triorganotin(IV) compounds inhibited ammonification, whereas higher concentrations enhanced ammonification. Complete inhibition of ammonification was attained 21–28 days after application of Thiram at 50 μg g^?1. On the other hand, with the triorganotin(IV) compounds, except for diphenylbutyltin bromide at 10–50 μg g^?1, ammonification persisted at all concentrations 28 days after application.     

Divalent NI Compounds: Identifying new Carbocyclic Carbenes to Design Nitreones using Quantum Chemical Methods

Nitreones are compounds with oxidation state 1 at the nitrogen, these compounds carry formal positive charge as well as two lone pairs of electrons at nitrogen center. These compounds are also known as divalent N^I compounds and can be represented with the general formula L → N⁺ ← L, where L is an electron donating ligand. In the recent past, several divalent N^I compounds have been reported with L = N-heterocyclic carbene (NHC), remote N-heterocyclic carbene (rNHC), carbocyclic carbene (CCC) and diaminocarbene. Recently, our group reported that a novel six-membered CCC (cyclohexa-2,5-diene-4-[diaminomethynyl]-1-ylidene) can stabilize N⁺ center in nitreones. As an independent carbene, this species is very unstable. In this work, modulation of this CCC using (a) annulation, (b) heterocyclic ring modification, (c) substitutions adjacent to the carbenic carbon, (d) exocyclic double bond insertion and (e) ring contraction, has been reported. These modulations and quantum chemical analyses helped in the identification of five new six-membered CCCs which carry improved donation and stability properties. Further, these CCCs were employed in the design of new divalent N^I compounds (nitreones) which carry coordination bonds between ligands and N⁺ center. The molecular and electronic structure properties, and the donor→acceptor coordination interactions present in the resultant low oxidation state divalent N^I compounds have been explored.     

13C Fourier transform studies of organotin compounds : I. 119Sn-13C spin-spin coupling constants

¹¹⁹Sn-¹³C coupling constants have been measured for fourteen organotin compounds including aliphatic, unsaturated and cyclic derivatives yielding results which indicate that these parameters have great potential for revealing information concerning structures and conformations of organotin compounds and of other compounds into which organotin groups can be conveniently introduced.     

New polyacetylenes from the sponge Siphonochalina sp.

Six new compounds, characterized by a long unsaturated alkyl chain (nC₂₂), were isolated from a marine sponge. All compounds except for one, possess an enyne terminus on one side of the molecule and either a terminal acetylene (in four) or a propargyl alcohol on the other end. Four of the compounds were unequivocally identified mainly by spectroscopic methods.Acetylenic compounds are well-known constituents of plants: only few, however, are known from marine organisms and to our knowledge only one group of compounds contains more than a single triple bond. Among the acetylene containing marine natural products are: A group of halogenated ethers, characterized by a straight-chain C-15 carbon skeleton and a terminal enyne function which has been isolated from algae¹ and a sea hare², carotenoids³, two steroids⁴, a sesquiterpene⁵ and polyketids^6,7.A diacetylene was found in a group of several n C-22 straight-chain compounds isolated from a marine sponge⁸. One of the compounds found in the latter sponge contains, again, the enyne terminus - an end group which turns out to be quite abundant in the above and the herewith discussed compounds.In our continuing search for bioactive compounds from marine organisms we have isolated from the sponge $\text{Siphonochalina sp}$.⁹ collected at several places in the southern part of the Gulf of Eilat (the Red Sea) six n C-22 straight-chain acetylenic compounds.Extraction of the freeze-dryed sponge (petrol ether, 4% dry weight) and subsequent repeated chromatographies (LH-20 and Silica gel)^10,11 gave six closely related new compounds, named in order of polarity, Δ¹⁵-docos-1-yne ($\text{1}$; RF^12a=0.65; 0.2% based on the dry weight of the animal), octahydrosiphonochalyne ($\text{2}$; Rf^12a=0.55; 0.4%), dihydrosiphonochalyne ($\text{4}$; Rf^12a=0.44; 0.1%) siphonochalyne ($\text{3}$; Rf^12b=0.34; 0.2%), dehydrosiphonochalynol ($\text{6}$; Rf^12b=0.55; 0.1%) and siphonochalynol ($\text{5}$; Rf^12b=0.43; 0.3%).     

Fluorescence sensors for Cu2+ based on conjugated indole Schiff base

Two new conjugated Schiff bases were prepared by condensation reactions between indole derivatives and o-phenylenediamine, respectively. The structures of the synthetic compounds were characterized by IR, ¹H NMR, and elemental analysis. And the melting point determination revealed that both compounds have good thermal stability. Their fluorescence measurements indicated that both compounds in solution have excellent performance on fluorescence emission, and the intensity of fluorescence emissions was quenched sharply by adding copper (II) nitrate. And the spectral changes were examined upon addition of various metal ions, such as Cu²⁺, Cd²⁺, Co²⁺, Ni²⁺, and Zn²⁺. The results indicated that the fluorescence intensity of two compounds quenched dramatically, and the quenching efficiency of Cu²⁺ was the highest.     

Synthesis and biological activities of new 1H‐1,2,4‐triazole alcohol derivatives containing a ferrocenyl moiety

Fourteen new 1H‐1,2,4‐triazole alcohol derivatives containing a ferrocenyl moiety were synthesized. In addition, six unexpected compounds, the hydroxyls of the title compounds, methylated by methanol, were obtained. The structures of all these new compounds were confirmed using ¹H NMR spectra, ¹³C NMR, MS and elemental analyses. Some compounds were also confirmed with IR spectra. The antifungal and plant growth regulatory activities of the title compounds are discussed. Copyright © 2008 John Wiley & Sons, Ltd.     

π-Extended Pyrrole-Fused Heteropine: Synthesis,Properties, and Application in Organic Field-Effect Transistors

Sulfur-embedded polycyclic aromatic compounds have been used as building blocks for numerous organic semiconductors over the past few decades. While the success is based on thiophene-containing compounds, aromatic compounds that contain thiepine, a sulfur-containing seven-membered-ring arene, has been less well investigated. Here we report the synthesis and properties of π-extended pyrrole-fused heteropine compounds such as thiepine and oxepine. A π-extended pyrrole-fused thiepine exhibited a “pitched π-stacking” structure in the crystal, and exhibited a high charge carrier mobility of up to 1.0 cm² V⁻¹ s⁻¹ in single-crystal field-effect transistors.     

A 3D‐QSAR Study of Celebrex‐Based Pdk1 Inhibitors Using Comfa Method

A 3D‐QSAR study of celebrex‐based compounds of PDK1 inhibitors using comparative molecular field analysis (CoMFA) was carried out. The structures of the compounds were obtained using quantum chemistry calculation. CoMFA calculations for a number of grouped subsets of compounds gave q² values of correlation in the range from 0 to 0.8. The low q² values should be mainly due to the narrow span of biological activity. Calculations for several subsets of 11–13 compounds gave high q² values, with 0.5–0.8. Factors affecting the results of the calculations are discussed. Calculated results with high q² values suggest that further chemical modifications of the compounds could lead to enhanced activity and could be an aid in the design of celebrex‐based cancer drugs.     

Purity Determination of Phosphorus Compounds by Internat- Standard31 P Nmr Spectroscopy. an Experimental Study and Validation

Abstract

Due to the proportionality between the area of the NMR signal and the number of nuclei, internal standard³¹P NMR spectroscopy is in principle a rapid and simple method for determination of the purity of phosphorus compounds.nuclei, internal standard³¹P NMR spectroscopy is in principle a rapid and simple method for determination of the purity of phosphorus compounds.nuclei, internal standard³¹P NMR spectroscopy is in principle a rapid and simple method for determination of the purity of phosphorus compounds.nuclei, internal standard³¹P NMR spectroscopy is in principle a rapid and simple method for determination of the purity of phosphorus compounds.     

Mass spectra of some α-substituted phenyl-α,α′-dimethoxyl ketones and their derivatives

The mass spectra of some α-substituted phenyl-α,α′-dimethoxyl ketones (compounds 1) and their 2,4-dinitrophenylhydrazones (compounds 2) and semicarbazones (compounds 3) have been studied. The characteristic fragments at m/z (M ? 73) from compounds 1, m/z (M ? 253) from compounds 2 and m/z (M ? 130) from compounds 3 are abundant and proposed to be [ArCROCH₃]⁺. Fragmentations yielding [M⁺ ? 49] from compounds 2 are abnormal and probably involve the methoxyl and nitro groups. The intense peak at m/z 130 due to [CH₃OCH₂CNNHCONH₂]⁺ from compounds 3 corresponds to α-cleavage of the molecular ion. Some other fragments from these new compounds are interpreted in this paper.