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81.
82.
Simon Doherty Julian G. Knight Tom H. Scanlan Mark R. J. Elsegood William Clegg 《Journal of organometallic chemistry》2002,650(1-2):231-248
The aprotic and protic bi- and multidentate iminophosphines 2-Ph2PC6H4N=CR1R2 (R1=H, R2=Ph=2a; R1=Me R2=Ph=2b; R1=H, R2=2-thienyl=2c; R1=H, R2=C6H4-2-PPh2=2d; R1=H, R2=C6H4-2-OH=2e, R1=H, R2=C6H4-2-OH-3-But=2f; R1=H, R2=CH2C(O)Me=2g) have been prepared by the acid catalyzed condensation of 2-(diphenylphosphino)aniline with the corresponding aldehyde–ketone. Iminophosphine 2d can be reduced with sodium cyanoborohydride to give the corresponding amino-diphosphine 2-Ph2PC6H4N(H)CH2C6H4-2-PPh2 (2h). In the presence of a stoichiometric quantity of acid, 2-(diphenylphosphino)aniline reacts in an unexpected manner with benzaldehyde, salicylaldehyde, or acetophenone to give the corresponding 2,3-dihydro-1H-benzo[1,3]azaphosphol-3-ium salts and with pyridine-2-carboxaldehyde to give N-(pyridin-2-ylmethyl)-2-diphenylphosphinoylaniline, the latter of which has been characterized by single-crystal X-ray crystallography, as its palladium dichloride derivative. The attempted condensation of 2-(diphenylphosphino)aniline with pyridine-2-carboxaldehyde to give the corresponding pyridine-functionalized iminophosphine resulted in an unusual transformation involving the diastereoselective addition of two equivalents of aldehyde to give 1,2-dipyridin-2-yl-2-(o-diphenylphosphinoyl)phenylamino-ethanol, which has been characterized by a single-crystal X-ray structure determination. The bidentate iminophosphine 2-Ph2PC6H4N=C(H)Ph reacts with [(cycloocta-1,5-diene)PdClX] X=Cl, Me) to give [Pd{2-Ph2PC6H4N=C(H)Ph}ClX] and the imino-diphosphine 2-Ph2PC6H4N=C(H)C6H4-PPh2 reacts with [(cycloocta-1,5-diene)PdClMe] to give [Pd{2-Ph2PC6H4N=C(H)C6H4---PPh2}ClMe] and each has been characterized by single-crystal X-ray crystallography. The monobasic iminophosphine 2-Ph2PC6H4N=C(Me)CH2C(O)Me reacts with [Ni(PPh3)2Cl2] in the presence of NaH to give the phosphino–ketoiminate complex [Ni{2-Ph2PC6H4N=C(Me)CHC(O)Me}Cl], which has been structurally characterized. Mixtures of iminophosphines 2a–h and a palladium source catalyze the Suzuki cross coupling of 4-bromoacetophenone with phenyl boronic acid. The efficiency of these catalysts show a marked dependence on the palladium source, catalysts formed from [Pd2(OAc)6] giving consistently higher conversions than those formed from [Pd2(dba)3] and [PdCl2(MeCN)2]. Catalysts formed from neutral bi- and terdentate iminophosphines 2a–d gave significantly higher conversions than those formed from their monobasic counterparts 2e–f. Notably, under our conditions the conversions obtained with 2a–c compare favorably with those of the standards; catalysts formed from tris(2-tolyl)phosphine and tris(2,4-di-tert-butylphenyl)phosphite and a source of palladium. In addition, mixtures of [Ir(COD)Cl]2 and 2a–h are active for the hydrosilylation of acetophenone; in this case catalysts formed from monobasic iminophosphines 2e–f giving the highest conversions. 相似文献
83.
Walter K. Dean Gary L. Simon Paul M. Treichel Lawrence F. Dahl 《Journal of organometallic chemistry》1973,50(1):193-207
The accidental but intriguing synthesis of acetatobis(triphenylphosphine)dicarbonylmanganese(I), (CH3CO2)Mn(CO)2[P(C6H5)3]2, has been accomplished by the reaction of NaMn(CO)5 with (CH3)3SiCl followed by the addition of triphenylphosphine and acetic acid. A three-dimensional single-crystal X-ray diffraction analysis has shown an octahedral-like molecule containing a symmetrically oxygen-chelating acetate group, the first such group to be reported in a metal carbonyl complex. The two triphenylphosphine ligands occupy mutually trans positions with the two carbonyl ligands possessing the remaining cis sites in the octahedral complex. The compound crystallizes with four molecules in a monoclinic unit cell of space group symmetry and of dimensions a = 17.744(2) Å, b = 9.692(1) Å, c = 20.004(2) Å, and β = 106.195(4)°. The relatively long MnO(acetate) bond lengths [2.066(6) and 2.069(7) Å] and the relatively short MnCO bond lengths [1.701(12) and 1.760(13) Å] and the relatively short MnP(C6H5)3 bond lengths [2.260(3) and 2.275(3) Å], compared to the corresponding MnCO and MnP(C6H5)3 bond lengths in other manganese carbonyl triphenylphosphine complexes, are rationalized on the basis that the acetate ligand in this molecule functions primarily as a σ-donor. 相似文献
84.
A one-step batch procedure is described for purification of murine alpha-fetoprotein (AFP) by estradiol affinity chromatography. Various ratios of carbodiimide (C), diaminononame (D) and estradiol hemisuccinate (E) were tested to determine optimal conditions for AFP purification. Although yields of AFP ranged from 15 to 44% depending on the reagent ratio employed, AFP isolates free of other protein contaminants were achieved at C:D:E ratios of 10:10:1 with a 29% yield. Both estrone and estradiol proved efficient as elution agents to free AFP bound to the estradiol-Sepharose beads, but higher yields were produced with estrone. After isolation the estrogen-eluted AFP preparations were analyzed by (1) estradiol-binding assays, (2) third-party radiocoprecipitation, (3) inhibition of radioimmunoassay for estrone and estradiol and (4) exchange of unlabeled for radiolabeled estradiol. These results indicated that the steroid remained attached to the eluted AFP molecule. 相似文献
85.
From the study of the CuCuBrCu2?εSC solid cell in the range of cubic digenite and “high temperature” hexagonal chalcocite we have deduced the laws of variation of the deviation from stoichiometry and the holes concentration with the equilibrium partial pressure of sulfur (δ and p are found to be proportional to ). The electronic model corresponding to the formation of associations (V×CuV′Cu) in the presence of neutral vacancies V×Cu allows one to explain these laws. In the low temperature range (range of “low temperature” hexagonal chalcocite and orthorhombic chalcocite) the study of thermal variations of Hall coefficient permits us to propose the following models: (a) the deviation from stoichiometry of the “low temperature” hexagonal chalcocite is due to the simple ionized vacancies V′Cu; (b) the deviation from stoichiometry of the orthorhombic chalcocite is due to the vacancies V′Cu and to the associations (V×CuV×Cu). 相似文献
86.
Ursula E. Spichiger Rudolf Eugster E. Haase G. Rumpf Peter Gehrig Angela Schmid Bruno Rusterholz Wilhelm Simon 《Fresenius' Journal of Analytical Chemistry》1991,341(12):727-731
Summary The selectivity of a new magnesium ionophore (ETH 7025) induced in membranes of different compositions is experimentally studied in view of the ion activities in human serum. The required selectivity coefficient against calcium for the application of an ion-selective magnesium electrode to human serum is calculated for the worst case. Other critical parameters for the application of a liquid PVC-based ion-selective membrane to undiluted human serum discussed are: the sensor lifetime which is related to the lipophilicity of the carrier as well as the ruggedness of the membrane against interactions with components of the relatively lipophilic sample. 相似文献
87.
Khlobystov AN Brett MT Blake AJ Champness NR Gill PM O'Neill DP Teat SJ Wilson C Schröder M 《Journal of the American Chemical Society》2003,125(22):6753-6761
A series of structurally related binuclear metallacycles [Cd(NO(3))(2)L](2), where L is an angular exo-bidentate ligand, have been synthesized. Each metallacycle contains two coordinatively unsaturated, chiral metal centers within a single molecule, and the assembly of these metallacycles into polymeric framework structures has been studied systematically for the first time. Stereoselective homochiral association of [Cd(NO(3))(2)L](2) leads to the formation of helical coordination polymers, whereas meso type association results in nonhelical chain structures. The type of stereoselective aggregation depends on the conditions of self-assembly as well as on ligand functionality. Both helical and nonhelical polymeric complexes have been isolated for the metallacycle [Cd(NO(3))(2)(2,4'-pyacph)](2) (2,4'-pyacph = 2,4'-(4-ethynylphenyl)bipyridyl). Homochiral association results in the formation of helical [Cd(NO(3))]( infinity ) chains which link the binuclear [Cd(NO(3))(2)(2,4'-pyacph)](2) metallacycles into racemic two-dimensional sheets which contain both P and M [Cd(NO(3))]( infinity ) helices. In contrast, meso-association leads to the formation of nonhelical one-dimensional chains. It is shown that the product of homochiral association is predominately formed at room temperature and that of meso-association is generated at elevated temperatures. Thus, it may be concluded that the homochiral association appears to be energetically less favorable than the meso-association, a conclusion that has been confirmed by theoretical calculations of the crystal lattice energy. Several high-yield syntheses of bipyridyl-type ligands used for metallacyclic assembly are also reported. 相似文献
88.
A potassium-selective liquid-membrane microelectrode based on valinomycin is described. Tip diameters of about 2 μm as well as high discrimination against Na+, H3O+, acetylcholine and some other quaternary ammonium ions, allow the intracellular measurement of potassium ion activity changes. The inherently high membrane resistance of the neutral carrier-based microelectrodes is reduced by adding a lipophilic charge carrier to the valinomycin. Results are compared with those of classical microelectrodes. 相似文献
89.
Markus Lerchi Elmar Reitter Wilhelm Simon 《Analytical and bioanalytical chemistry》1994,349(4):272-276
A pulsed molecular beam Fourier transform microwave spectrometer especially designed for the quantitative analysis of polar pollutants in air is presented. This very fast method has a sensitivity in the ppm range and can be applied to a wide variety of substances. Details of the apparatus and the results of some performance tests are given. 相似文献
90.
Jürg K. Schneider Peter Hofstetter Ern Pretsch Daniel Ammann Wilhelm Simon 《Helvetica chimica acta》1980,63(1):217-224
N,N,N′,N′-Tetrabutyl-3,6-dioxaoctane-dithioamide, an Ionophore with Selectivity for Cd2+ The dioxa-dithioamide 3 behaves as a highly selective ionophore for Cd2+ in solvent polymeric membranes. It induces cation-permselectivity in these membranes with a transference number of 1 for Cd(NO3)2- and of 2 for CdCl2-solutions. In the presence of a proton carrier, 3 may be used to selectively pump Cd2+ through membranes by coupling with a pH gradient. 相似文献