Sulfur, chromium complex

Sulfane, ethynylpentafluoro-, 27 329 Sulfur, chromium complex, 27 69 cobalt, iron, and ruthenium complexes, 26 352... 

ReO , and Hg, however, only slightly. CrOj forms a similar complex, but the technetium complex can be separated from the chromium complex by extracting the former into carbon tetrachloride. According to Fujinaga et al. the method can be improved by the use of 1 M hydrochloric acid instead of sulfuric acid. 

MORDANT. A substance capable uf binding a dye to a textile liber. The mordant forms an insoluble lake in the liber, the color depending on the metal of the mordant. The most itnponanL mordants are trivaleni chromium complexes, metallic hydroxides, tannic acid. etc. Mordants are used with acid dyes, basic dyes, direct dyes, and sulfur dyes. Prcmetallized dyes contain chromium in the dye molecule. A mordant dye is a dye requiring use of a mordant 10 be effective. See also Dyes. 

REDUCTION, REAGENTS Bis(triphenyl-phosphine)copper tetrahydroborate. Borane-Pyridine. Calcium-Methylamine/ ethylenediaminc. Chlorobis(cyclopenta-dienyl)tetrahydroboratozirconium(IV). Chromium(II)-Amine complexes. Copper(0)-lsonitrile complexes. 2,2-Dihydroxy-l, 1-binaphthyl-Lithium aluminum hydride. Di-iododimethylsilane. Diisobutyl-aluminum 2,6-di-/-butylphenoxide. Diisobutyl aluminum hydride. Dimethyl sulfide-Trifluoroacetic anhydride. Disodium tetracarbonylferrate. Lithium-Ammonia. Lithium-Ethylenediamine. Lithium bronze. Lithium aluminum hydride. Lithium triethylborohydride. Potassium-Graphite. 1,3-Propanedithiol. Pyridine-Sulfur trioxide complex. 

Methyl-3,5-diphenyl-l//-thiopyran 1-oxide forms red air-stable complexes with carbonyls of chromium, molybdenum and tungsten. (78CB1709). X-Ray diffraction measurements on these compounds confirm the non-planarity of the thiabenzene oxide nucleus and reinforce the evidence for high inversion barriers at sulfur. These complexes are found in isomeric forms with either the sulfur-oxygen bond axial to the half-chair conformation adopted by the ring, or the S- methyl group axial the complexes cannot be interconverted. 

Pyridine forms a number of complexes and salts which are useful synthetic reagents. These include pyridinium hydrobromide perbromidc (CjHjNH Brj ), which is a convenient crystalline, easily handled, bromi-nating agent, the pyridine sulfur trioxide complex (C H NrSOj) for sul-fonations, pyridine borane (C HjNrBH,) for hydroborations and the pyridine-chromium(VI) oxide complex (CjHjNiCrOj) for oxidations. 

AsAgFsSi6, Arsenate, hexafluoro-, bis-(cycZo-octasulfur)silver(l -h), 24 74 AsBrsFgS, Arsenate, hexafluoro-, tribromo-sulfur(IV), 24 76 AsQH, Arsine, dimethyl-molybdenum complex, 25 169 AsCigHis, Arsine, triphenyl-chromium complexes, 23 38 ASC24H10, Arsonium, tetraphenyl-... 

It is not always necessary to start with gem-dihalides for the synthesis of aldehydes or ketones. There is a process by which carbonyl compounds can be obtained from monohalides, sometimes in excellent yield for instance, when 3-chlorocyclopentene is stirred vigorously with aqueous sodium dichromate solution at 0°, a chromium complex of 2-cyclopenten-l-one is formed, and this is decomposed to give a 60-68% yield of the ketone if 50% sulfuric acid is dropped in carefully with cooling 513 and 1,2-cyclopentanedione can be obtained in 80% yield by dropwise addition of aqueous iron(m) chloride solution to 2-chlorocyclopentanone in water with rapid stirring at 100°.539... 

Alternatively, the arene can be left complexed so that the chemistry of the Ti -arene complex can be exploited (see Section 10.3). " The Dotz reaction between the cyclohexenyl carbene 8.52 and the benzylic alkyne 8.53 in the presence of a silylating agent gave the ti -complex 8.54 (Scheme 8.18). Treatment of this complex with LDA resulted in formation of the anion a- to sulfur 8.55 that cyclized by nucleophilic attack onto the chromium-complexed aromatic ring. Oxidative work-up then gave the tetracycle 8.57. 

Thiocarbamate (tc, RHNCSO-) is a monodentate ambidentate ligand, and both oxygen- and sulfur-bonded forms are known for the simple pentaamminecobalt(III) complexes. These undergo redox reactions with chromium(II) ion in water via attack at the remote O or S atom of the S- and O-bound isomers respectively, with a structural trans effect suggested to direct the facile electron transfer in the former.1045 A cobalt-promoted synthesis utilizing the residual nucleophilicity of the coordinated hydroxide in [Co(NH3)5(OH)]2+ in reaction with MeNCS in (MeO)3PO solvent leads to the O-bonded monothiocarbamate, which isomerizes by an intramolecular mechanism to the S-bound isomer in water.1046... 

As it was not known what kind of organic matter acts as the major ligand for chromium in seawater, Nakayama et al. [38] used ethylene diaminetetra-acetic acid (EDTA) and 8-quinolinol-4-sulfuric acid to examine the collection and decomposition of organic chromium species, because these ligands form quite stable water-soluble complexes with chromium (III), although they are not actually present in seawater. Both of these chromium (III) chelates are stable in seawater at pH 8.1 and are hardly collected with either of the hydrated oxides. The organic chromium species were then decomposed to inorganic... 

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