Cobalt diaqua

Diaquabis(diimine)metaI(IU) complexes, acid dissociation constants, 37 394-395 cis-Diaqua cobalt complexes, 45 290 Diarsatriptycene, skeleton, 33 33 Diarsenatophosphates, 4 61-62 Diarsine... 

The cis/trans isomerization reaction, Eq. (24), has been applied in the preparation of salts of the cis isomers of the chromium(III) complexes with L3 = (NH3)3 or tacn (319). For these species Eq. (24) equilibrium is shifted to the right, while the corresponding equilibria with the diaqua or dihydroxo species, respectively, are shifted to the left (Table X). The increased stability of the cis aqua hydroxo species can be explained in terms of intramolecular hydrogen bond formations (Section VI,C). As mentioned above, the corresponding cobalt(III) and rhodium(III) complexes have been isolated as salts only in the case of the trans-(H20)L3M(0H)2ML3(H20)4+ cations, but it seems very probable that their cis isomers could be prepared by reaction Eq. (24). 

The data in Table XXXV show that common features for these ammonia and amine complexes are very fast isomerization between the cis and trans isomers of the diaqua species and the fact that the trans diaqua isomers are generally more stable than the cis isomers. In the ammine system the activation parameters for k2 and k 2 are consistent with an isomerization process at cobalt(III), but it is at present not clear how this occurs. It need not be a simple cis-trans isomerization occurring at one of the Co(III) centers, but might involve the participation of both metal centers. The isomerization reaction may proceed via intramolecular proton transfer between a water ligand and one of the two hydroxo bridges with simultaneous bridge cleavage and formation... 

Besides (carbonato)bis(ethylenediamine)cobalt(III) chloride and the corresponding bromide salt, the following complexes are described cis- and frara -dichlorobis(ethylenediamine)cobalt(III) chloride, cts-aquachlorobis(ethylenediamine)cobalt(III) sulfate, cis-bis(ethylenediamine)dinitrocobalt(III) nitrite, m-aquabis-(ethylenediamine)hydroxocobalt(III) dithionate, and cis-diaqua-bis(ethylenediamine)cobalt(III) bromide. 

To 27.5 g. (0.1 mole) of crude (carbonato)bis(ethylenediamine)-cobalt(III) chloride is added 200 ml. of 1.00 N hydrochloric acid. The carbonato complex is dissolved with evolution of carbon dioxide gas and formation of a red solution consisting primarily of the corresponding cw-diaqua species. The solution is evaporated in the steam bath until an almost dry paste has been formed. The purple residue is filtered and washed with three 20-ml. portions of ice-cold water. Drying in air yields 19.5 g. of purple crystals of cu-dichlorobis(ethylenediamine)cobalt(III) chloride. The mother liquor and the washings are again evaporated almost to dryness to yield a second crop of crystals, 5.9 g. The total yield is 25.4 g. (84% based on (carbonato)bis(ethylenediamine)cobalt(III) chloride). The analysis and the visible absorption spectrum of the two fractions are identical. Anal. Calcd. for [Co(en)2Cl2 ] C1 H20 Co, 19.42 N, 18.46 C, 15.82 Cl, 35.05 H, 5.98. Found Co, 19.50 N, 18.57 C, 15.77 C1, 35.15 H, 6.01. 

In the literature cis-[tetraammineaquahydroxocobalt(Ill)] sulfate has been prepared from cis-[tetraamminediaquacobalt(IIl)] sulfate, which is prepared from [tetraammine(carbonato)cobalt(lII)] sulfate. In the method described here cis-[tetraammineaquahydroxocobalt(III)] dithionate is prepared in this manner from [tetraammine(carbonato)cobalt(III)] sulfate by way of the cis-diaqua salt, which is isolated only as a crude product. [Tetraammine(carbonato)-cobalt(III)] sulfate is easily obtained in higli yield from cobalt(Il) sulfate. ... 

The dinuclear complex di-/i-hydroxo-bis[nitrilotriacetatocobaltate(m)] may be hydrolysed in acid solution to give diaqua(nitrilacetato)cobalt(in). No more than two nitrogen atoms are thought to be co-ordinated, giving this complex moderate oxidative properties. The reactions with reducing substrates (S) show a two-term rate law ... 

Activation volumes for the substitution of diaqua-meso-tetrakis(lV-methyl-4-pyridyl)porphyrinato cobalt(III) by NCS have been determined and provide evidence for the dissociative mechanism shown in equations (5)-(7). 

The kinetics have been reported for the formation of several edta-5-sulfosalicylate ternary complexes of lanthanide ions, and ligand substitution in trimalonatovanadium(III) with edta and nta . Reports have also appeared on the formation of ternary complexes involving Fe(III), pyridoxamine, and pyridoxal and the formation of bis- and tris(acetohy-droxamato)Fe(III) and activation volume evidence has been provided for a dissociative mechanism in the reaction of thiocyanate with diaqua[mcso-tetrakis(Af-methyl-4-pyridyl)porphinato] cobalt(III). 

Cl2H3gClftC02Ng020 4 H2O, trans-Diaqua-di-M-hydroxo-bis[(l,4,7-tri-azacyclononane)cobalt(III)] tetraperchlorate tetrahydrate, 45B,... 

Electron transfer between V(IV) and I(V) (as 10J) catalyzed by Ru(VIII) and Os(VIII) and the inner-sphere oxidation of diaqua (nitrilotriacetato)cobalt(II) by 104 have both been studied kinetically. The radiolysis of 10 J and the photolysis of 10" in aqueous solution have also been studied. JV-iodosuccinimide and V(IV) react in a process first order in oxidant and inverse first order in acid [in contrast to the reaction involving V(IV) and... 

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