Chromium complexes perchlorates

Caution should be observed in handling this compound, as with all perchlorate salts. The tris(bipyridine)chromium(I1) perchlorate explodes violently on slow heating to 250° and can be set off by static electricity. It does not appear to be shock-sensitive on dropping an 8.8-g. steel ball from 4 ft., although the compound was tested only once. The explosive properties of related complexes have been described.16... 

Chromium(II) perchlorate is the salt of choice for preparing the en complex in dimethylformamide solution. At comparable concentration levels chromium(II) sulfate is insoluble, and the <-.lu-omium(lI) chloride - is only partially soluble in the i-( a< tion solution. 

A monophosphite complex has been prepared by the reaction of either chromium(III) perchlorate 28 or chromate829 with the ligand. The related monohypophosphite complex [Cr(H20)4H2P02]2+ has also been reported.830... 

The complex [Cr(DMF)6][Cl04]3 has been prepared from the reaction of chromium(III) perchlorate with DMF (90 °C, 10 h).951 Solvent exchange and substitution proceed by h mechanisms.947,952 The complex [Cr(DMF)6]Br3-DMF was prepared by the reaction of chromium metal with bromine in DMF 953 the electronic spectrum of this complex was very similar to that of the perchlorate salt. 

Chromic Azide Complexes. See Chromium Azide Complexes in Vol 1, pA530-R and also Azidopentammine-chromium (III) Perchlorate, Chloropentamminechromium (III) Azide and Hexamminechromium Azide on pA277 under Ammines... 

The general formula [RCr(OH2)s] + describes this group of complexes. Reaction of an alkyl halide with chromium(II) perchlorate in perchloric acid yields these... 

A mixture of dimethylformamide and ethylenediamine is stirred magnetically under nitrogen and an aqueous solution of chromium(ll) perchlorate is added with a hypodermic syringe to form a purple solution complex. A solution of 1.66 g. of 1-bromo-naphthalene in oxygen-free dimethylformamide is added, and the mixture is stirred until the colour changes from purple to deep red, and then poured into aqueous hydrochloric acid extraction with ether and workup affords 0.96-1.00 g. of naphthalene. 

Copper(i).—Copper(i) has been prepared in non-complexing perchlorate media in a metastable form by the reduction of copper(ii) by vanadium(ii) and chromium(ii), the solutions ( 10 mol 1 ) being stable for some hours if maintained in an oxygen-free atmosphere out of contact of metallic surfaces. The reduction of cobaltammine complexes has been investigated ... 

The synthesis and spectral properties of a series of nickel(II) perchlorate and chromium(III) perchlorate complexes of the substituted amides have been reported. Based on measured electronic parameters of these amide complexes, a series of amides have been arranged in the following order in the spectrochemical series ... 

The cobalt complex is usually formed in a hot acetate-acetic acid medium. After the formation of the cobalt colour, hydrochloric acid or nitric acid is added to decompose the complexes of most of the other heavy metals present. Iron, copper, cerium(IV), chromium(III and VI), nickel, vanadyl vanadium, and copper interfere when present in appreciable quantities. Excess of the reagent minimises the interference of iron(II) iron(III) can be removed by diethyl ether extraction from a hydrochloric acid solution. Most of the interferences can be eliminated by treatment with potassium bromate, followed by the addition of an alkali fluoride. Cobalt may also be isolated by dithizone extraction from a basic medium after copper has been removed (if necessary) from acidic solution. An alumina column may also be used to adsorb the cobalt nitroso-R-chelate anion in the presence of perchloric acid, the other elements are eluted with warm 1M nitric acid, and finally the cobalt complex with 1M sulphuric acid, and the absorbance measured at 500 nm. 

An interesting alternative to the use of chromium(VI) oxidants for the conversion of 1 to 2 involves the use of a low-valent iron reagent prepared in situ by the action of hydrogen peroxide on an iron(II) complex of 1 (73). Vinblastine (as the free base) is treated with 2 equiv of perchloric acid in acetonitrile at -20°C. Ferrous perchlorate is then added, followed by the addition of excess 30% hydrogen peroxide. Work-up of the reaction mixture with a saturated solution of ammonium hydroxide gives 2 in yields of 35-50% after chromatography. 

Chloro-5-thiophenethiol, 50,106 3a-Cholestanol, 50, IS Chromium(II)-en perchlorate, 52, 62 Chromium(II) salts, standardization procedure for solutions, 52, 64 Chromium trioxide-pyridine complex, 52,5... 

HCrO ] has been shown to be the photo-active species in the photochemical reaction of dilute solutions of chromium(vi) oxyacids with alcoholic reducing agents. The association of chromate with Np , Th, and Fe" in perchlorate solution has been studied spectrophotometrically and the respective formation constants, 63.6,4.70, and 1.93, have been determined. The greater stability of the Np complex has been interpreted in terms of the limited donation of 5/-electron density from Np to the d-orbitals of chromium in the chromate ion. ... 

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