A series of carbonyl derivatives of 5-imino-Δ3-1,2,4-thiadiazolines has been prepared and shown by X-ray analysis of a selected example to have a trithiapentalene-like structure. When diphenylketene was used as acylating reagent, the primary product ( 14 ), obtained at room temperature, rearranged on heating in a polar solvent into a Δ2-thiazolin-4-one ( 15 ). The structure of 15 has been confirmed by X-ray analysis, and shown to be a zwitterion. Rearranged products (i.e., 16 and 20-22 ) were also obtained when 3 was reacted with dimethyl acetylenedicarboxylate or methanesulfonyl chloride, whereas tosyl chloride gave normal tosylated derivatives ( 17-19 ). The latter have also a nearly linear N-S…O arrangement, but the interaction between S and O is weak. 相似文献
In this paper, we present a variable temperature (2)H solid-state NMR investigation of cryptophane-E:chloroform and cryptophane-E:dichloromethane inclusion complexes. The (2)H line shapes and nuclear spin relaxation rates were analyzed in terms of the distribution of C-D bond orientations and the time scale of the guest dynamics. It was found that encaged chloroform produces broad (2)H spectra, and that its reorientation is relatively slow with a correlation time of approximately 0.17 mus at 292 K. In contrast, the (2)H line shapes of encaged dichloromethane are narrow and the motion of this guest molecule is fast with a correlation time of approximately 1.4 ps at 283 K. The (2)H NMR data were complemented by an X-ray diffraction study of the cryptophane-E:dichloromethane structure, which was utilized in the analysis of the NMR parameters. 相似文献
The η-hexamethylbenzenehydridoruthenium(II) complexes RuHCl(η-C6Me6)L (L = PPh3 (11), AsPh3 (12), P(C6H4-p-F)3 (14), P(C6H4-p-Me)3 (15), P(C6H4-p-OMe)3 (16), P-t-BuPh2 (17), P-i-PrPh2 (18), P-i-Pr3 (19), PCy3 (20) and P-t-BuMe2 (21)) have been made by heating [RuCl2(η-C6Me6)]2, the ligand and sodium carbonate in propan-2-ol. The triarylphosphine complexes 11, 14 and 15 react with methyllithium to give aryl ortho-metallated hydridoruthenium(II) complexes such as Ph2)(η-C6Me6) (22) and 19 similarly gives the isopropyl cyclometallated complex -i-Pr2(η-C6Me6) (29) as a mixture of diastereomers. Reaction of 17 with methyllithium gives initially the t-butyl cyclometallated complex Ph2)(η-C6Me6) (25) which isomerizes by a first order process (k.2 h?1 in C6D6 or THF-d8 at 50°C) to the aryl ortho-metallated complex -t-BuPh)(η-C6Me6) (26). The similarly generated isopropyl cyclometallated complex Ph2)(η-C6Me6) (27) has not been isolated in a pure state owing to rapid isomerization to -i-PrPh)(η-C6Me6) (28); both 27 and 28 exist as a pair of diastereomers. The formation of the cyclometallated complexes and the isomerizations are thought to involve intermediate 16-electron ruthenium(O) complexes Ru(η-C6Me6)L. 相似文献
Summary. Photoredox reactions occurring in irradiated methanolic solutions of trans-[Fe(N2O2) (CH3OH)N3], where N2O22– are tetradentate open-chain N2O2-Schiff base N,N-ethylenebis(R-salicylaldiminato) or N,N-1-methylethylenebis(R-salicylaldiminato) ligands denoted as R-salen and R-sal(Me)en, respectively (R=H, 5-Cl, 5-Br, 4-OCH3), have been investigated and their mechanism has been proposed. The complexes are redox stable in the dark. Ultraviolet and/or visible irradiation of methanolic solutions of the complexes induces photoreduction of Fe(III) to Fe(II). As an intermediate, CH2OH radicals were identified by EPR spin trapping technique. The final product of the photooxidation coupled with the photoreduction of Fe(III) is formaldehyde. The efficiency of the photoredox processes is strongly wavelength dependent and influenced by the peripheral groups R of the tetradentate ligands. Differences between the course of photochemical changes induced by 254nm radiation and the other wavelengths of incident radiation is rationalized by involving azide anions photoreactivity in observed redox changes. 相似文献
Coupling between19F and magnetic nuclei (1H,17O) in water molecules in the first hydration sphere of F? are calculated using Monte Carlo simulations. The simulations are based on intermolecular potentials from the literature and on variations of coupling constants with geometry obtained by coupled Hartree-Fock calculations. Average coupling constants are ≈20–40 Hz. Intermolecular scalar relaxation in aqueous solutions is discussed. 相似文献
Aerobic oxidation of toluene (PhCH3) is investigated by complementary experimental and theoretical methodologies. Whereas the reaction of the chain‐carrying benzylperoxyl radicals with the substrate produces predominantly benzyl hydroperoxide, benzyl alcohol and benzaldehyde originate mainly from subsequent propagation of the hydroperoxide product. Nevertheless, a significant fraction of benzaldehyde is also produced in primary PhCH3 propagation, presumably via proton rather than hydrogen transfer. An equimolar amount of benzyl alcohol, together with benzoic acid, is additionally produced in the tertiary propagation of PhCHO with benzylperoxyl radicals. The “hot” oxy radicals generated in this step can also abstract aromatic hydrogen atoms from PhCH3, and this results in production of cresols, known inhibitors of radical‐chain reactions. The very fast benzyl peroxyl‐initiated co‐oxidation of benzyl alcohol generates HO2. radicals, along with benzaldehyde. This reaction also causes a decrease in the overall oxidation rate, due to the fast chain‐terminating reaction of HO2. with the benzylperoxyl radicals, which causes a loss of chain carriers. Moreover, due to the fast equilibrium PhCH2OOH+HO2.?PhCH2OO.+H2O2, and the much lower reactivity of H2O2 compared to PhCH2OOH, the fast co‐oxidation of the alcohol means that HO2. gradually takes over the role of benzylperoxyl as principal chain carrier. This drastically changes the autoxidation mechanism and, among other things, causes a sharp decrease in the hydroperoxide yield. 相似文献
Immunoassays based on chemiluminescence for the measurement of serum and plasma steroids (estradiol, estriol, progesterone, testosterone, and cortisol), urinary steroid conjugates (estrone-3-glucuronide, estriol-16α-glucuronide and pregnanediol-3α-glucuronide) and peptide hormones (choriogonadotropin and luteinizing hormone) are surveyed briefly. These immunoassays are simple, robust and valid alternatives to radioimmunoassay. Homogeneous procedures and recent solid-phase assays based on purified specific antibodies, covalently coupled to polymer beads are discussed. Some new results are presented for solid-phase chemiluminescence immunoassays: estradiol is quantified in extracts of serum by using a monoclonal antibody to estradiol with estradiol-6-carboxymethyloxime-aminobutylethyl isoluminol as the marker ligand, and progesterone is quantified in unextracted serum by using a polyclonal antibody to progesterone, progesterone-11-hemisuccinyl-aminobutylethyl isoluminol as the marker ligand, and danazol (17α-pregna-2,4-dien-20-yno[2,3-d]-isoxazol-17-ol) to displace progesterone from serum binding-proteins. Their clinical utility is demonstrated. 相似文献
In the crystal structure of the title compound, C9H9NO3, there are strong intramolecular O—H⋯N and intermolecular O—H⋯O hydrogen bonds which, together with weak intermolecular C—H⋯O hydrogen bonds, lead to the formation of infinite chains of molecules. The calculated intermolecular hydrogen‐bond energies are −11.3 and −2.7 kJ mol−1, respectively, showing the dominant role of the O—H⋯O hydrogen bonding. A natural bond orbital analysis revealed the electron contribution of the lone pairs of the oxazoline N and O atoms, and of the two hydroxy O atoms, to the order of the relevant bonds. 相似文献
Non-empirical calculations of the field gradient tensor at the chlorine nucleus are resorted for chloromethane, trichloromethane, chlorosilane and trichlorosilane. The calculations agree quite well with the experimental quadrupole coupling constants. The calculated asymmetry parameters in trichloromethane and trichlorosilane are low and the principal z axis of the field gradient tensor is found nearly to coincide with the CCl and SiCl bond directions. 相似文献