Ammonia chromium complexes

Another example of an unusual reaction occurring in the gas phase is ammonia in a chromium complex ion being substituted by arenes such as benzene (4). It is important to note the uncommon oxidation state of the chromium. 

Unlike the corresponding 1 1 chromium complexes, the stability of 1 1 cobalt-dye complexes is inadequate for them to be obtained in acceptable yield at low pH. However, advantage can be taken of the strong affinity for cobalt ions of ammonia or amines as... 

In reactions involving coordination compounds, the metal acts as the Lewis acid (electron-pair acceptor), while the ligand acts as a Lewis base (electron-pair donor). In the reaction above, the ammonia ligand displaced the water ligand from the chromium complex because nitrogen is a better electron-pair donor (less electronegative) than oxygen. 

Platinum forms both platinous and platinie salts, in which the metal is divalent and tetravalent respectively. Both series of salts are capable of uniting with ammonia, forming complex ammines. The co-ordination number in the platinous series is four and in the platinie series six. The latter series correspond in many respects to the chromic and cobaltic ammino-salts, but as the metal is tetravalent, the maximum number of radicles outside the complex is four instead of three. Also, the ammino-bases from which the salts are derived are much more stable than those of chromium or cobalt. 

Dinuclear dihydroxo-bridged complexes can often be obtained from the parent mononuclear complexes by the solid-state reaction Eq. (7). This was first reported by Werner (7, 11) and Dubsky (18), and it is generally the most convenient method for the preparation of dihydroxo-bridged complexes of Cr(III), Co(III), Rh(III), and Ir(III) with L4 = (NH3)4 or (en)2 [and (tn)2 in the case of chromium(III)] (67, 131, 133, 214 219). With the exception of the ammonia chromium(III) complex, these reactions are essentially quantitative and the rate of reaction follows the order chromium(III) > cobalt(III) > rhodium(III) >... 

A number of substituted benzenes, naphthalenes, indans, pyridmes, and indoles form arene(tricarbonyl)chromium complexes upon thermolysis under an inert atmosphere, usually in a high boiling ether, or by irradiation of the arenes in the presence of chromium hexacarbonyl. The complexes are relatively air-stable and can usually be stored for long periods in the absence of light. Somewhat milder conditions can be used by transfer of the chromium tricarbonyl group from preformed naphthalene(tricarbonyl)chromium, tris(L)tricarbonyl chromium (L = acetonitrile, ammonia, pyridine), or tricarbonyl( -l-methylpyrrole)chromium. Enan-tiomerically pure arene(tricarbonyl)chromium complexes having two different substituents, either ortho or meta can be prepared conveniently by classical resolution of racemic... 

Pentacarbonyl(carbene)chromium complexes with a primary amino group at the alkenyl terminus 32, readily obtained by addition of ammonia to alkynyl-substituted complexes, initially rearranged upon heating to pentacarbonylchromium-coordinated 1-azabuta-l,3-dienes 33, which subsequently underwent [4 + 2] cycloaddition of an alkyne to give coordinated 4-ethoxy-1,4-dihydropyridines the corresponding pyridines, e.g. 34, were formed by 1,4-elimination of ethanol. ... 

Improvement in the preparation of the trans-diamminebis-(ethylene-diamine)cobalt(III) ion has allowed a quantitative spectral evaluation of the products of the ammonatlon(acid ammonolysis). For example, one product of an inversion reaction has been found to consist of about 65% trans-diammine, 22%L -cis-diammine, and 13%D -cis-diammine. Extension of these studies to chromium complexes in ammonia has given no indication of comparable inversions. 

Naphthalene is an efficient sensitizer for the photoaquation of chrom-ium(m) complexes. Both [Cr(NH8) ] and [Cr(NH3)6Cl] + lose ammonia, to produce [Cr(NH3)5(OHa)] + and ciJ-[Cr(NH3)4(OH2)a] +, respectively. Energy is transferred to the chromium(ra) complex from the lowest triplet state of the naphthalene. Bimolecular quenching constants of naphthalene by several chromium complexes, including [Cr(NH3)8Q] +, have been determined by flash spectroscopy. ... 

Naphthalenediol. 1,5-Dihydroxynaphthalene or Asurol is a colorless material which darkens on exposure to air. It is manufactured by the fusion of disodium 1,5-naphthalenedisulfonate with sodium hydroxide at ca 320°C in high yield. 1,5-Naphthalenediol is an important coupling component, giving ortho-a2o dyes which form complexes with chromium. The metallised dyes produce fast black shades on wool. 1,5-Naphthalenediol can be aminated with ammonia under pressure to 1,5-naphthalenediamine. 

Ammonia forms a great variety of addition or coordination compounds (qv), also called ammoniates, ia analogy with hydrates. Thus CaCl2 bNH and CuSO TNH are comparable to CaCl2 6H20 and CuSO 4H20, respectively, and, when regarded as coordination compounds, are called ammines and written as complexes, eg, [Cu(NH2)4]S04. The solubiHty ia water of such compounds is often quite different from the solubiHty of the parent salts. For example, silver chloride, AgQ., is almost iasoluble ia water, whereas [Ag(NH2)2]Cl is readily soluble. Thus silver chloride dissolves ia aqueous ammonia. Similar reactions take place with other water iasoluble silver and copper salts. Many ammines can be obtained ia a crystalline form, particularly those of cobalt, chromium, and platinum. 

Table 7.31 lists data for the corrosion of nickel and some nickel alloys by ammonia at 500°C. At higher temperatures the more complex hardened nickel-chromium-base alloys are more resistant than the binary alloys and... 

The precipitate is soluble in free mineral acids (even as little as is liberated by reaction in neutral solution), in solutions containing more than 50 per cent of ethanol by volume, in hot water (0.6 mg per 100 mL), and in concentrated ammoniacal solutions of cobalt salts, but is insoluble in dilute ammonia solution, in solutions of ammonium salts, and in dilute acetic (ethanoic) acid-sodium acetate solutions. Large amounts of aqueous ammonia and of cobalt, zinc, or copper retard the precipitation extra reagent must be added, for these elements consume dimethylglyoxime to form various soluble compounds. Better results are obtained in the presence of cobalt, manganese, or zinc by adding sodium or ammonium acetate to precipitate the complex iron(III), aluminium, and chromium(III) must, however, be absent. 

Balthis and Bailar6 obtained tris (ethylenediamine) chromium-(III) complexes by the oxidation of chromium(II) solutions, using a procedure somewhat similar to that used for the synthesis of cobalt (III) com plexes. Mori7 described the preparation of hexaamminechromium(III) salts from the oxidation of chromium (II) salts in the presence of ammonia. The results obtained in both syntheses have been erratic.8,9 Berman noted that the foregoing syntheses are rendered dependable by the use of a catalyst of activated platinum on asbestos. Schaeffer,100 in a subsequent study, independently used colloidal platinum as a catalyst but reported some difficulty in separating it from the product.106 The procedures recommended and described here are based on the use of platinized asbestos as the catalyst. 

In these procedures 1 litre of seawater was shaken with 60 mg charcoal for 15 min. Complexing agents were added in amounts of 1 mg, dissolved in 1 ml of acetone. The pH was 5.5, or it was adjusted to 8.5 by addition of 0.1 M ammonia. The charcoal was filtered off and irradiated. Results of three sets of experiments with charcoal alone, charcoal in the presence of dithizone, and charcoal in the presence of sodium diethyldithiocarbamate are compared. The following elements are adsorbed to an extent from 75 to 100% silver, gold, cerium, cadmium, cobalt, chromium, europium, iron, mercury, lanthanum, scandium, uranium, and zinc. The amount of sodium is reduced to about 10 6, bromine to about 10 5, and calcium to about 10 2. 

Spectra of a variety of chromium compoimds in the +3 valence state are included in Fig. 16. The principal peak is centered at about 22-25 ev. in all cases. The CrjOa spectrum is almost identical to that of Mn02 of Fig. 5. Spectra of the oxalato complex and the ammonia complex are almost identical to spectra of the corresponding cobalt compounds of Figs. 13 and 11. 

Forms a number of coordination compounds (ammonia complex) with several metals adds to AgCl forming soluble complex [Ag(NH3)2]Cl forms tetraamine complex [Cu(NH3)4]S04 with CUSO4 and forms many hexaamine complexes with cobalt, chromium, palladium, platinum and other metals. 

Carbazole will react with 1 or 2 mol of ferrocene in hot decalin in the presence of aluminium-aluminium chloride producing crystalline derivatives in which either one or both" of the benzene rings is linked to iron, 25 and 26, respectively. The sandwich compound 25 was deprotonated to 27 with sodamide in liquid ammonia. A chromium carbonyl complex 28... 

The reaction of iminium ions with dihydropyridines is a method, suggested from biosynthetic studies, for the formation of carbon-carbon bonds to these six-membered heterocycles. The 1,4-dihydropyridine (8), a presumed intermediate from the reaction of ammonia with glutaraldehyde, reacts with the cyclic iminium ion (159) to give, after oxidation, nicotine (160) (72CC1091). Another example of this reaction has provided a total synthesis of olivacine (163). The 1,2-dihydropyridine ring system in (161), generated from its chromium tricarbonyl complex, was observed to undergo an intramolecular cyclization... 

Additive or more-than-additive toxicity of free cyanide to aquatic fauna has been reported in combination with ammonia (Smith et al. 1979 Leduc et al. 1982 Alabaster et al. 1983 Leduc 1984) or arsenic (Leduc 1984). However, conflicting reports on the toxicity of mixtures of HCN with zinc or chromium (Towill et al. 1978 Smith et al. 1979 Leduc et al. 1982 Leduc 1984) require clarification. Formation of the nickelocyanide complex markedly reduces the toxicity of both cyanide and nickel at high concentrations in alkaline pH. At lower concentrations and acidic pH, solutions increase in toxicity by more than 1000-fold, owing to dissociation of the metallo-cyanide complex to form hydrogen cyanide (Towill et al. 1978). Mixtures of cyanide and ammonia may interfere with seaward migration of Atlantic salmon smolts under conditions of low dissolved oxygen (Alabaster et al. 1983). The 96-h toxicity of mixtures of sodium cyanide and nickel sulfate to fathead minnows is influenced by water alkalinity and pH. Toxicity decreased with increasing alkalinity and pH from 0.42 mg CN/L at 5 mg CaCOj/L and pH 6.5, to 1.4 mg CN/L at 70 mg CaCOj/L and pH 7.5 to 730 mg CN/L at 192 mg CaCOj/L and pH 8.0 (Doudoroff 1956). 

Ephraim and Muller 2 describe some results obtained with the groups — S04, — Se04, —Mo04, — W04, and —Cr04. These anions were united with the hexammino-nickel complex, and the temperature measured at which the ammonia tension is equal to atmospheric pressure. The stability of the complex is apparently independent of the atomic volumes of selenium, sulphur, chromium, molybdenum, and tungsten, but increases proportionally with the molecular volume of the corresponding trioxides. 

Chromium in the trivalent state forms a variety of salts, the most important and the simplest being the violet salts, which liberate in aqueous solution chromium cation Cr" A green series of chromic salts, isomeric with the violet salts, liberate in aqueous solution some chromium cation, whilst part of the chromium is present as a complex ion. With weak acids, sulphurous, hydrocyanic, or thiocyanic acids, the chromic ion forms complex ions of great stability. Finally, a very large group of salts exists where chromium associated with ammonia forms the complex ion, the chromi-ammines. 

Chromium has a maximum co-ordination number of six the chromium atom, therefore, may combine with, at most, six monovalent atoms or groups, over and above its ordinary valency value, with formation of a complex radicle. Hence chromic chloride is capable of associating with, or adding on, six molecules of ammonia with formation of the derivative, [Cr(NH3)8]Cl3. Ammonia may be replaced by a substituted ammonia group or some other basic group, such as alkyl amine, pyridine, or ethylenediamine. 

Ammonia unites readily with iridium salts, giving rise to complex ammino-derivatives. The first compounds described appear to be ammines analogous to those of palladium and platinum, to which they were compared by Berzelius 8 and Skoblikoff.4 A further series were described by Claus 5 wliich he represented like those of ammino-rhodium salts, as they bore a marked resemblance to these. After Jorgensen had established the constitution of the ammines of rhodium, cobalt, and chromium salts, Palmaer gave similar constitution to the iridium compounds. 

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