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11.
Unit cell parameters have been calculated from x-ray powder diffraction data of Mo2Br4
Py
4 (A), Mo2I4
Py
4 (B), Mo2I4
Pic
4 (C), Mo2(SCN)4
Py
4 (D) and Mo2(SCN)4
Pic
4 (E), A, B and C crystallize tetragonal. A witha=9,42,c=15,O2 Å; B witha=9,46,c=14,98 Å and C witha=9,66 andc=15,72 Å D and E crystallize orthorhombic. D witha=10,09,b=9,14,c=15,08 Å; E witha=10,22,b=9,41 andc=15,15 Å.Py=pyridine,Pic=4-methylpyridine. 相似文献
12.
Summary The substitution of phosphine in the [RhCl(COD)(phosphine)] complex (1), where phosphine is PPh3 or 1/2 BPS-2 [bis(diphenylphosphinoethyl)tetramethyldisiloxane] and COD is cycloocta-1,5-diene, by 1-hexene is a two-step reversible reaction. All individual rate constants and equilibrium constants were determined spectrophotometrically and associative mechanism occurring via the formation of five-coordinated [RhCl(COD)(phosphine)(1-hexene)] (2) was inferred. The rate-determining step changes from the first- to the second-one as the concentration of 1-hexene increases. An excess of phosphine shifts the equilibrium towards complex (2). 相似文献
13.
A master equation is used to study transitions between the stable limit cycle and stable focus in the two-variable bistable system. The distribution function of the mean first passage time between these attractors and the relative dispersion of the mean first return time from the stable focus to itself as a function of the intensity of fluctuations are calculated and discussed. A coherence resonance is observed for the return time from the focus to itself. 相似文献
14.
15.
Zenon Lukaszewski Andrzej Szymanski Bogdan Wyrwas 《Trends in analytical chemistry : TRAC》1996,15(10):1239-531
The evolution of the BiAS procedure is reviewed and its standard recommended version was compared with the modified version combined with the indirect tensammetric method (BiAS-ITM). New applications of the use of BiAS-ITM for the determination of nonionic surfactants (in the presence of hydrocarbons or adsorbed on particles) and polyethylene glycols were discussed. 相似文献
16.
A study of reactions of dimeric siloxide iridium complex, [[(cod)Ir(mu-OSiMe3)]2] (1) with vinyltriethoxysilane and vinyltrimethoxysilane has revealed a new type of the reation--alkoxy group transfer from silicon to iridium with a simultaneous transfer of a siloxy group from iridium to silicon--as a result of which vinyldialkoxytrimethyldisiloxane and dimeric alkoxide iridium complex [[(cod)Ir(mu-OR)]2] (3) are formed. The structure of [[(cod)Ir(mu-OEt)]2] (3a) has been solved by X-ray diffraction. 相似文献
17.
A sensitive (1 ng ml?1) liquid chromatographic method with fluorescence detection is described for the determination of arprinocid and analogous compounds in human plasma. The method is based on chemical derivatization with chloroacetaldehyde to form highly fluorescent derivatives. Extraction of the drug from plasma and separation of the derivative from the reaction mixture are accomplished by solid-phase extraction with two silica cartridges. The effects of pH, solvent, and concentration of the reagents on the efficiency of derivatization were studied. The assay in plasma was validated in the 1–50 ng ml?1 range. The fluorescent derivatives were synthesized and fully characterized. The derivatives were also found to be efficient as energy acceptors in the oxalate ester/hydrogen peroxide chemiluminescent system. 相似文献
18.
Marciniec B Majchrzak M Prukała W Kubicki M Chadyniak D 《The Journal of organic chemistry》2005,70(21):8550-8555
(E)-N-(Silyl)vinylcarbazole has been easily prepared via a new catalytic route, silylative coupling (SC) of vinylcarbazole with vinyltrisubstituted silanes catalyzed by [RuH(Cl)(CO)(PCy3)2]. X-ray structures of two silylvinylcarbazoles as first N-vinylcarbazole derivatives have been resolved. The Pd-catalyzed Hiyama coupling reaction (also as the tandem reaction with SC) of synthesized (E)-N-(triethoxysilyl)vinylcarbazole with iodobenzene has been performed to afford (E)-N-(phenylvinyl)carbazole with high yield and stereoselectivity. 相似文献
19.
Krystyna B. Lesiak Bogdan Uznanski Paul F. Torrence 《Applied biochemistry and biotechnology》1997,67(1-2):33-44
To increase the accessibility of 8-bromo-2′,5′-oligoadenylates, we developed a synthesis of 2′-5′-linked oligoriboadenylates containing varying numbers of 8-bromoadenosine residues based on the use of a CPG-LCA solid support and the phosphoramidite approach. Although N6benzoyl protection was satisfactory for incorporation of nonmodified adenine residues into 2′,5′-oligonucleotides, the effective incorporation of 8-bromoadenine into such 2′,5′-linked oligomers required use of a non acyl protecting group. Amidine protection of the purine exocyclic amino function proved compatible with all aspects of the phophoramidite approach and with the hydroxyl protection groups employed. 相似文献
20.
Zdyrko B Varshney SK Luzinov I 《Langmuir : the ACS journal of surfaces and colloids》2004,20(16):6727-6735
This work describes studying the permanent grafting of carboxylic acid end-functionalized poly(ethylene glycol) methyl ether (PEG) chains of different molecular weights from the melt onto a surface employing poly(glycidyl methacrylate) ultrathin film as an anchoring layer. The grafting led to the synthesis of the complete PEG brushes possessing exceptionally high grafting density. The maximum thickness of the attached PEG films was strongly dependent on the length of the polymer chains being grafted. The maximum grafting efficiency was close to the critical entanglement molecular weight region for PEG. All grafted PEG layers were in the "brush regime", since the distance between grafting sites for the layers was lower than the end-to-end distance for the anchored macromolecules. Scanning probe microscopy revealed that the grafting process led to complete PEG layers with surface smoothness on a nanometric scale. Practically all samples were partly or fully covered with crystalline domains that disappeared when samples were scanned under water. Due to the PEG hydrophilic nature, the surface with the grafted layer exhibited a low (up to 21 degrees ) water contact angle. 相似文献