Kinetic parameters for aquation

Kinetic parameters for aquation at corresponding Cr(III) and Co(III) complexes have been compared for a series of complexes cis-[ML4XY]"+, where L4 = (NH3)4 or (en)2, X = Cl- or H20, and Y=an uncharged leaving group (DMSO, DMF, or DMAC). The uniformly negative activation volumes (AV between —2 and —11 cm3 mol-1) for the chromium complexes contrast with uniformly positive activation volumes (A V between +3 and +12 cm3 mol-1) for the cobalt complexes - AV values provide a more clear-cut contrast than AS values here (22). 

Table 8.2. Kinetic Parameters for Aquation (Nonacid-Catalyzed Path) of [Rh(NHs)sL] Cations, in Aqueous Solution at 353 K...

Aquation of /ra 5 -[CoCl(N3)en2]+, which results in loss of azide, is acid catalysed, but the limiting rate depends on the acid used. A study of rates as functions of added acid and added salts indicates that this limiting rate behaviour can be ascribed to the formation of ion-pairs of varying lability. Relevant to acid catalysis of aquation of azides is the characterisation of the perchlorate of the proposed protonated form in aquation, [Co(N3H)(NHg)5] +. Complexes of HP04 can be considered as equivalent to protonated forms of POi " complexes kinetic parameters for aquation of [Co(P04)(NH3)s] and of [Co(P04H)(NH8)5]+ have been obtained. ... 

Stereochemistry is important in controlling the reactivity of copper(ii) complexes of tet-a, tet-b, and trans- A-d a [formulae (7), (7), (8)]. Strongly acidic conditions are required for aquation of complexes of these fairly inflexible ligands. A more widely ranging study led to the determination of kinetic parameters for aquation of zinc(ii), cadmium(ii), copper(ii), nickel(ii), and cobalt(ii) complexes of some bi-, tri-, and quadri-dentate macrocyclic ligands, e.g. bis-pyridylisoindole (18)T ... 

Table 4 Kinetic parameters for aquation of bisdioxime complexes [Co(LLH)a(S03H)(Cl)], as their ammonium salts at 30 C solvent compositions % by weight...

Table 8 Kinetic parameters for aquation of chromium(iu)-chloride complexes loss of first chloride in each case)...

Table 4 Kinetic parameters for aquation of [PdX4] anions...

The kinetics of ring closure of the complex cw-[Co(en)2(OH2)-(NHaCHaCHaOH)] have been studied, and are consistent with the non-observance of this species in the aquation of cw-[Co(en)2(NH2CHaCH20H)X] + cations. An associative mechanism for the ring closure of the aquo-ethanol-amine complex is proposed. The kinetics and mechanisms of analogous ring-closure reactions of similar platinum(n) complexes are discussed in the appropriate section of Chapter 2 of this Part. Kinetic parameters for aquation of the isomeric cations cw-[Co(en)2LBr]2+ with L = 3- or 4-methylpyridine show the expected similarity. ... 

The complexes m-[Co(phen)2(N02)X]+, with X = Cl or Br, are slightly more distant cousins of the complexes mentioned so far in this section. Kinetic parameters for aquation of these complexes, and of cis-[Co(phen)2Cl2l for comparison, are reported in Table 3. The slight difference in reactivity between the chloronitro- and the dichloro-complexes masks much greater but compensating differences in the activation pmameters. 

Dioximato-complexes. Kinetic parameters for aquation of a range of... 

Kinetic parameters for aquation of /ra j-[Co(LL)(LLH)(N02)2] anions are similar for LLH = cyclopentanedionedioximeandcyclohexanedionedioxime. The activation enthalpies for aquation of these complexes are rather less than for the analogous dimethylglyoxime complex. Rates of aquation of these complexes are a function of the pH of the medium, as protonation of nitro-ligands is possible. ... 

The kinetic pattern for aquation of the newly characterized iU-amido-At-selenato-dicobalt complex (11) is similar to that established for its / -amido-A -sulphato-analogue. In both cases the product is (12), and there is strong kinetic evidence for transient intermediates of the type (13). A rate law of the form shown in equation (4) above operates kinetic parameters for aquation of the Ai-amido-jM-selenato-complex are included in Table 6. A preliminary report on the kinetics of aquation of the closely related acetato-complex (14) indicates that the rate law of equation (4) also applies here, but the rate law for aquation of the yU-amido-/ -phosphato-complex (15) is more complicated. 

Table 9 Kinetic parameters for aquation of nitrito-chromium m) complexes kx and k% are defined by the rate law cited in the text, MI and AS are derived from the respective kx and kz values. Rate constants are quoted at 25 °C ...

Table 10 Kinetic parameters for aquation of chromium(m) complexes subscripts 0 and 1 refer to kinetic pathways defined by equation (5) in the text...

Table 15 Kinetic parameters for aquation of ruthenium n) complexes...

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