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141.
Michael I. Bruce Ernst Horn Janis G. Matisons Michael R. Snow 《Journal of organometallic chemistry》1985,286(2):271-287
The reactions of Os3(μ-H)2(CO)10 with a series of Group IB metal acetylide-tertiary phosphine complexes are described. Whereas the compounds M(C2C6F5)(PPh3) (M = Cu, Ag, Au) afforded the complexes MOs3(μ-CHCHC6F5)(CO)10(PPh3) cleanly and in high yield, complex mixtures of products were obtained from reactions of the analogous phenylacetylides. The complexes MOs3(μ-CHCHPh)(CO)10(PPh3), MOs3(μ-CHCHPh)(CO)9(PPh3)2 and MOs3(μ-H)(CO)10(PPh3) (of known structure), and MOs3(μ-CHCHPh)(CO)9(PPh3)2 and HMOs3(CHCPh)(CO)8 (of unknown structure) were characterised; Au(C2Ph)(PMe3) afforded similar derivatives. The reactions proceed by oxidative-addition and hydrogen migration steps; MP bond cleavage reactions also occur to a small extent. The molecular structures of AuOs3(μ-CHCHC6R5)(CO)10(PPh3) (R = F or H) were determined by X-ray analyses. For R = F, crystals are triclinic, space group P with a 9.081(2), b 13.291(2), c 17.419(2) Å, α 84.49(1), β 76.20(2), γ 75.81(2)° and Z = 2; 4622 observed data [I > 2.5σ(I)] were refined to R = 0.027, RW = 0.031. For R = H, crystals are triclinic, space group P, with a 9.403(4), b 13.448(3), c 13.774(4) Å, α 83.34(2), β 88.66(3), γ 70.21(3)°, and Z = 2; 4405 observed data [I > 2.5σ(I)] were refined to R = 0.030, RW = 0.033. The two molecules differ in the orientation of the Ph rings of the PPh3 groups, but are otherwise similar to Os3(μ-H)(μ-CHCHBut)(CO)10 with the μ-H ligand replaced by the isolobal μ-Au(PPh3) group. 相似文献
142.
Synthesis, Crystal Structure and Spectroscopic Properties of the Cluster Anions [(Mo6Br )X ]2? with Xa = F, Cl, Br, I The tetrabutylammonium (TBA), tetraphenylphosphonium (TPP) and tetraphenylarsonium (TPAs) salts of the octa-μ3-bromo-hexahalogeno-octahedro-hexamolybdate(2?) anions [(Mo6Br)X]2? (Xa = F, Cl, Br, I) are synthesized from solutions of the free acids H2[(Mo6Br)X] · 8 H2O with Xa = Cl, Br, I. The crystal structures show systematic stretchings in the Mo? Mo bond length and a slight compression of the Bri8 cube in the Fa to Ia series. The cations do not change much. The i.r. and Raman spectra show at 10 K almost constant frequencies of the (Mo6Bri8) cluster vibrations, whereas all modes with Xa ligand contribution are characteristically shifted. The most important bands are assigned by polarization measurements and the force constants are derived from normal coordinate analysis. The 95Mo nmr signals are shifted to lower field with increasing electronegativity of the Xa ligands. The fluorine compound shows a sharp 19F nmr singlet at ?184.5 ppm. 相似文献
143.
144.
Alam MS Kim IJ Nemati B O'Neill JJ Romero V Severini H Sun CR Wang P Zoeller MM Crawford G Fulton R Gan KK Kagan H Kass R Lee J Malchow R Morrow F Sung M White C Whitmore J Wilson P Butler F Fu X Kalbfleisch G Lambrecht M Skubic P Snow J Bortoletto D Brown DN Dominick J McIlwain RL Miao T Miller DH Modesitt M Schaffner SF Shibata EI Shipsey IP Battle M Ernst J Kroha H Roberts S Sparks K Thorndike EH Wang C Artuso M Goldberg M Haupt T Horwitz N Kennett R Moneti GC Playfer S Rozen Y Rubin P 《Physical review D: Particles and fields》1992,46(11):4822-4827
145.
On the Synthesis of Sulfonated Derivatives of 2,3-Dimethylaniline and 3,4-Dimethylaniline Baking the hydrogensulfate salt of 2,3-dimethylaniline ( 1 ) or of 3,4-dimethylaniline ( 2 ) led to 4-amino-2,3-dimethylbenzenesulfonic acid ( 4 ) and 2-amino-4,5-dimethylbenzenesulfonic acid ( 5 ), respectively (Scheme 1). The sulfonic acid 5 was also obtained by treatment of 2 with sulfuric acid or by reaction of 2 with amidosulfuric acid. 3-Amino-4,5-dimethylbenzenesulfonic acid ( 3 ) and 5-Amino-2,3-dimethylbenzenesulfonic acid ( 6 ) were prepared by sulfonation of 1,2-dimethyl-3-nitrobenzene ( 9 ) to 3,4-dimethyl-5-nitrobenzenesulfonic acid ( 11 ) and of 1,2-dimethyl-4-nitrobenzene ( 10 ) to 2,3-dimethyl-5-nitrobenzenesulfonic acid ( 12 ), respectively, with subsequent Béchamp reduction (Scheme 1). Preparations of 2-amino-3,4-dimethylbenzenesulfonic acid ( 7 ) and of 6-amino-2,3-dimethylbenzenesulfonic acid ( 8 ) were achieved by the sulfur dioxide treatment of the diazonium chlorides derived from 3,4-dimethyl-2-nitroaniline ( 24 ) and from 2,3-dimethyl-6-nitroaniline ( 31 ) to 3,4-dimethyl-2-nitrobenzenesulfonyl chloride ( 29 ) and 2,3-dimethyl-6-nitrobenzenesulfonyl chloride ( 32 ), respectively, followed by hydrolysis to 3,4-dimethyl-2-nitrobenzenesulfonic acid ( 30 ) and 2,3-dimethyl-6-nitrobenzenesulfonic acid ( 33 ), and final reduction (Scheme 3). Compound 7 was also synthesized by reaction of 4-chloro-2,3-dimethylaniline ( 23 ) with amidosulfuric acid to 2-amino-5-chloro-3,4-dimethylbenzenesulfonic acid ( 20 ) and subsequent hydrogenolysis (Scheme 2). 4′-Bromo-2′, 3′-dimethyl-acetanilide ( 13 ) and 4′-chloro-2′, 3′-dimethyl-acetanilide ( 14 ) on treatment with oleum yielded 5-acetylamino-2-bromo-3,4-dimethylbenzenesulfonic acid ( 17 ) and 5-acetylamino-2-chloro-3,4-dimethylbenzenesulfonic acid ( 18 ), respectively. Their structures were proven by hydrolysis to 5-amino-2-bromo-3,4-dimethylbenzenesulfonic acid ( 21 ) and 5-amino-2-chloro-3,4-dimethylbenzenesulfonic acid ( 22 ), followed by reductive dehalogenation to 3 . 相似文献
146.
The synthesis of dimetallic olefin complexes of the type L1M1C7H7M2L2 (M1 = Fe, Co, Rh; M2 = Rh, Ir, Pd; L1 = CO, C5H5; L2 = diene, allyl, P(OR)3) is described. The fluxional structures were investigated by 13C-, 57Fe- and 103Rh-NMR.-spectroscopy, and a cisoid dimetallic coordination, including a (metal, metal)-bond, can be deduced for the C7H7-ring. 57Fe- and 103Rh-chemical shifts give indications for the charge distribution in the 34e-complexes. The homodimetallic complex (Cp)Rh(tropone)Rh(Cp) ( 13 , Cp = cyclopentadienyl) and the corresponding 2-methoxytropone complex 14 were synthesized in addition to the above mentioned complexes. A fluxional bis(1-3-η-allyl)-coordination of the two Rh-atoms was derived from the temperature-dependent 13C-NMR.-spectra. A spin simulation of the (Cp)-multiplets of 12 and 13 yields information about (Rh, Rh)-spin-coupling which amounts to ≈5 Hz at 30°. 相似文献
147.
Beat Ernst Reinhold Oehrlein Daniel Bellu Jozef Gonda Rainer Jeschke Udo Nubbemeyer 《Helvetica chimica acta》1997,80(3):876-891
A novel type of ketene-Claisen rearrangement in which the precursor of the rearrangement is generated in situ by reaction of optically active allyl thioethers with dichloroketene is described. A characteristic feature of this rearrangement is the excellent chemoselectivity in favor of allyl thioethers vs. allyl ethers, i.e., exclusive chirality transfer of the allylic sulfur moiety is observed with 12, 13 , and 25--27 . The cyclic, optically active allyl thioethers (+)-(R)- 4 and (?)-(S)- 4 and the open-chain allyl thioethers 11--13 rearrange with in situ generated dichloroketene to the optically active thioesters (?)-(S)- 28 , (+)-(R)- 28 , and 31-33 , respectively. A chirality-transfer of > 99% in the cyclic cases (+)-(R)- 4 and (?)-(S)- 4 , and 96--98 % in the open-chain cases 11--13 is observed. Furthermore, the dichloroketene-Claisen rearrangement is characterized by a high asymmetric 1,2-induction. The chiral allylic sulfides 25--27 give the optically active thioesters 36--38 with a 1,2-induction > 99% as determined by NMR-shift experiments. 相似文献
148.
149.
E. Scheubeck und O. Ernst 《Fresenius' Journal of Analytical Chemistry》1971,254(3):185-187
Zusammenfassung Die Probe wird mit Salpetersäure in Gegenwart von Silbernitrat gelöst. Das entstandene Silberchlorid trennt man durch Zentrifugieren ab und zersetzt es anschließend mit Chromschwefelsäure in einer Bestimmungsapparatur. Dabei entstehende flüchtige Chlorverbindungen werden in einer schwefelsauren Kaliumpermanganatlösung zu Chlor oxydiert, das mit o-Tolidin ein gelbes Oxydationsprodukt bildet. Die Extinktion dieser Gelbfärbung wird photometrisch gemessen und die entsprechenden Chloridmengen an Eichgeraden ermittelt. 1–100 g Chlorid können bestimmt werden. Die Standardabweichung beträgt für den Bereich 1–10 ppm maximal ±0,6 ppm Cl und bei der Bestimmung von etwa 200 ppm maximal ± 2,8 ppm Cl.
Wir danken Herrn Dr. G. Iwantscheff, Forschungslaboratorien der Siemens AG, für wertvolle Anregungen und Herrn Dr. v. Sturm, Forschungslaboratorien der Siemens AG, für die Überlassung von polarographisch ermittelten Chlorgehalten in Selenproben. 相似文献
Photometric determination of small amounts of chloride in selenium, tellurium, gallium and bismuth
The sample is dissolved in nitric acid in presence of silver nitrate. The silver chloride is separated by centrifuge and decomposed in a glass equipment by chromosulphuric acid. Resulting volatile compounds of chlorine are oxidized by potassium permanganate in sulphuric acid solution to chlorine, which forms with o-tolidine a yellow oxidation product. The absorbance of this coloration is measured by photometry and corresponding amounts of chloride are found out by calibration curves. 1 to 100 g of chloride can be determined in the range of 1 to 10 ppm Cl with a standard deviation of ±0.6 ppm Cl and at approximately 200 ppm Cl with ± 2.8 ppm Cl.
Wir danken Herrn Dr. G. Iwantscheff, Forschungslaboratorien der Siemens AG, für wertvolle Anregungen und Herrn Dr. v. Sturm, Forschungslaboratorien der Siemens AG, für die Überlassung von polarographisch ermittelten Chlorgehalten in Selenproben. 相似文献
150.
Paul Von Ragué Schleyer José Walkimar De M. Carneiro 《Journal of computational chemistry》1992,13(8):997-1003
The closely related Cs ( 1 ) and C2v ( 3 ) structures of CH have been reinvestigated at many ab initio levels using MP2/6-31G** and MP2/6-311 + + G(2df, 2pd) geometries. The largest basis sets employed were 6-311G(3df, 2p), 6-311 + + G(3df, 3pd), and the Dunning “correlation consistent” polarized triple-split valence basis set (cc-pVTZ). Electron correlation was probed at the MP4 level, but the QCISD method was also used with the largest basis sets. While electron correlation favors 3 over 1 by about 2 kcal/mol, the correlated relative energies with all basis sets employed range from 0.36–1.03 kcal/mol in favor of 1 . The best estimate of this difference, 0.86 kcal/mol, is essentially identical with the (scaled) zero-point energy difference, 0.84 kcal/mol, favoring 3 over 1 . These results indicate that 1 and 3 have almost exactly the same energy at 0 K. Our best value for the dissociation energy of CH is 42.0 kcal/mol [QCISD(T)/6-311 + + G(3df, 3pd)//MP2(fu)/6-311 + + G(2df, 2pd), corrected to 298 K], which agrees very well with the experimental value. © 1992 by John Wiley & Sons, Inc. 相似文献