Inert complex ions

Hexa.cya.no Complexes. Ferrocyanide [13408-63 ] (hexakiscyanoferrate-(4—)), (Fe(CN) ) , is formed by reaction of iron(II) salts with excess aqueous cyanide. The reaction results in the release of 360 kJ/mol (86 kcal/mol) of heat. The thermodynamic stabiUty of the anion accounts for the success of the original method of synthesis, fusing nitrogenous animal residues (blood, horn, hides, etc) with iron and potassium carbonate. Chemical or electrolytic oxidation of the complex ion affords ferricyanide [13408-62-3] (hexakiscyanoferrate(3—)), [Fe(CN)g] , which has a formation constant that is larger by a factor of 10. However, hexakiscyanoferrate(3—) caimot be prepared by direct reaction of iron(III) and cyanide because significant amounts of iron(III) hydroxide also form. Hexacyanoferrate(4—) is quite inert and is nontoxic. In contrast, hexacyanoferrate(3—) is toxic because it is more labile and cyanide dissociates readily. Both complexes Hberate HCN upon addition of acids. 

For continuing polymerization to occur, the ion pair must display reasonable stabiUty. Strongly nucleophilic anions, such as C/ , are not suitable, because the ion pair is unstable with respect to THE and the alkyl haUde. A counterion of relatively low nucleophilicity is required to achieve a controlled and continuing polymerization. Examples of anions of suitably low nucleophilicity are complex ions such as SbE , AsF , PF , SbCf, BE 4, or other anions that can reversibly coUapse to a covalent ester species CF SO, FSO, and CIO . In order to achieve reproducible and predictable results in the cationic polymerization of THE, it is necessary to use pure, dry reagents and dry conditions. High vacuum techniques are required for theoretical studies. Careful work in an inert atmosphere, such as dry nitrogen, is satisfactory for many purposes, including commercial synthesis. 

Electron transfer between metal ions contained in complexes can occur in two different ways, depending on the nature of the metal complexes that are present. If the complexes are inert, electron transfer occurring faster than the substitution processes must occur without breaking the bond between the metal and ligand. Such electron transfers are said to take place by an outer sphere mechanism. Thus, each metal ion remains attached to its original ligands and the electron is transferred through the coordination spheres of the metal ions. 

X 10-3 sec.-1, was found for the dissociation of water. However, when ClOr was replaced by NO3 " as the inert anion the rates were up to 30% slower and the curvature of the k0b vs. (Cl ) plot was considerably lessened. A dependence on the nature of the inert anion would not be expected for this mechanism. The curvature cannot be explained by preassociation of chloride and complex ions. This would have to be much larger than is expected for 2 1 electrolytes of this type and no spectrophotometric evidence for it was obtained. 

A Co(IH) complex is inert in ligand-substitution reactions, and its uniform structure is thus maintained even in an aqueous solution. The reaction mechanism of a Co(III) complex in solution is well known, so that a pendant-type polymer-Co(IU) complex, e.g. 17,19, is one of the most suitable compounds for a quantitative study of the effects of a polymer ligand on the reactivity of a metal complex. The reactivities of the polymer-Co(III) complexes are discussed here kinetically and compared with those of the monomeric Co(III) complexes in the following reactions electron-transfer reactions between the polymer complexes and Fe(II) [Eqs. (5) and (6)], and the ligand-substitution reaction of the polymer-Co(III) complex with hydroxy ions or water [Eqs. (7) and (8)J. One of the electron-transfer reactions proceeds via... 

The formation of vinyl acetate from vinyl chloride, although not formally an oxidation process, is pertinent to the oxidation of ethylene by palladium acetate complexes. The inertness of vinyl chloride to nucleophilic substitution is modified considerably by coordination to Pd(II). Thus, chloride is readily displaced5 5 3-5 5 6 from vinyl chloride by acetate ion in the presence of catalytic amounts of Pd(II) ... 

The complex ions, in which the central ion has not the inert gas configuration, are very numerous these are especially formed with readily polarizable ions, such as Cl, (Br, I), CN, CNS and S. In these cases the polarization as well as the Van der Waals-London energy can contribute to the heat of formation of the complex. The following are examples K4CdCl6, K2[Hg(CN)4], Ks[Ag(SCN)J, KFeS2 etc. 

It is interesting to compare the extent of proton transfer determined for complexes in inert matrices with those observed in the gas phase and predicted by ab initio computations. Consistent with the latter, H N-HF is found to be a neutral pair in Ar matrix , but the complex is somewhat more polar than it is in the gas phase. In fact, the frequency shift of the HF stretch rises quite noticeably as the polarizability of the matrix increases from Ar to N2. One can hence expect the matrix results to typically indicate greater proton transfer character than observed in the gas phase. Nonetheless, HF does not appear to form an ion pair with even stronger bases such as trimethylamine in Ar ", nor with In fact, HF... 

Cobalt(III) hexaammine is quite inert to hydrolysis. In strongly basic media ([OH ] = 0.1 to 2.1 M) the reaction rate increases and [OH ] apparently reaches a limiting value around 1 M, where the reaction becomes independent of [OH ], 3 x 10 s at 61.8°, (i = 2.0 (157). The mechanism of the reaction involves the SnI(CB) pathway. The limiting rate observed at high pH is thought to refiect a pre-equilibrium ion pair formation between the complex ion and OH , rather than the first-order reaction of the fuly deprotonated complex ion. The rate of... 

The high-spin complex [Cr(H20)5] is labile, but the low-spin complex ion [Cr(CN)f f is inert. Explain. 

Since the cobalt(II) complex is inert, its decomposition (114) even in acidic medium k = 1.2 x 10-2 mol T s ) is slow compared with the electron-transfer rate ()e = 5.0 mohU s" ). Therefore, process (113) dominates, and no photoeffect has been observed. The inertness of the [Co(sep)] + cation in photochemical processes is caused by complete encapsulation of the cobalt ion. In the system with the nonmacrocyclic hexamine [Co(NHs)6] trication, photoreduction was found to occur in relatively high quantum yield ( = 0.16). In this case, the photocomposition rate of [Co (NH3)5(NH3)+] + cation formed on irradiation k > 10 s >) is higher than that of electron transfer k = 10-5 mol-T s-i). 

It is common practice to consider the traditional Werner octahedral complex ions [MlLNle]" [M = Co(III), Rh(III), Ir(III), Cr(III), Ru(III), Pt(IV) LN = donor atom of unidentate or polydentate ammine or amine] as well as square-planar [M(LN)4p [M = Pt(II), Pd(II)] as kinetically inert compounds. Bound ammonia is generally less labile than bound water, and it has been suggested that this observation can be related to the presence of an extra and exposed electron pair in water. This may make it more sensitive to electrophilic groups in the solvation sheath, which could assist its dissociation from the metal ion (274). If we take the stance of assigning lability as a property of the ligand in such complexes, then ammonia and amines in general can be... 

A mechanistic study of the reaction of ruthenium ammine complexes with NO was reported almost four decades earlier. Although [Ru(NH3)6] is very inert, an acidic solution of this complex ion was observed to undergo a rapid reaction in the presence of NO to form [Ru(NH3)s(NO)]. [164] An electrophilic substitution process was invoked, with NO considered to function as an electrophile and the product proposed to be Ru -NO". The conclusion from a subsequent study was that a bond making mechanism operates for this... 

When equilibrium is reached, the concentration of the [Co(NH3)6] + ion is very low. However, this reaction requires several days to complete because of the inermess of the [Co(NH3)g] + ion. This is an example of an inert complex, a complex ion that undergoes very slow exchange reactions (on the order of hours or even days). It shows that a thermodynamically unstable species is not necessarily chemically reactive. The rate of reaction is determined by the energy of activation, which is high in this case. 

Most complex ions containing Co, Cr, and Pt are kinetically inert. Becanse they exchange ligands very slowly, they are easy to study in solntion. As a resnlt, onr knowledge of the bonding, strnctnre, and isomerism of coordination componnds has come largely from stndies of these compounds. 

Inert complex. A complex ion that undergoes very slow ligand exchange reactions. (22.6)... 

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