Chloride anation rate

Water Exchange, Chloride Aquation and Chloride Anation Rates for [MlNHalsX)" Compounds ... 

The rate constant for the base-catalysed hydrogen exchange of [Ir(NH3)6] at 298 K in D2O (reaction 64) has been determined (fc = 1.5 x 10 M s" ). The chloride anation of [Ir(H2)(NH3)5] + is three times faster than the water exchange rate, and has been attributed to an associative interchange mechanism. ... 

Pavelich " has presented a thorough study of the chloride anation of rra j-[Rh(en)2(H20)2f (equation 124), which implies that the conjugate base form (franj-[Rh(en)2(0H)(H20)] ) is much more reactive than had previously been thought. Between [H+] values of 0.02 M to 0.2 M, the observed rate is strongly, and linearly, proportional to Presumably due to the strong... 

These results give the following values of A(A5cr-co) in cal K mol -11.5 (DMSO), -10.2 (DMF), -17.9 (NMF), and -14.0 (formamide) Equilibria occur in DMSO and DMF and the concentration of added Cl affects both the position of these equilibrium and the rates of solvolysis. The chloride anation of [Co(tren)Cl(DMSO)] was also studied and found to occur by an (5n1)ip mechanism. A number of the solvolysis products have been isolated and characterized. There is evidence that tren may sterically block nucleophilic attack. 

Bridged Dicobalt Complexes.—Rate constants for the forward and reverse reactions of aquation and chloride anation for the equilibrium between (7) and (8) have been determined. The amido-bridged chloro-aquo-complex (8) can Equate further to give the amido-hydroxo-bridged species (9), which... 

Both the activation-volume and transition-enthalpy approaches have indicated considerable associative character to the mechanisms of substitution at the chromiumCm) " and rhodium(ra) complexes studied. In contrast, other workers have published evidence for D [5Nl(Iim)] substitution at other chromium(ra) and rhodium(ra) complexes. One example is provided by chloride anation of the [Rh(OH2)5Cl] + cation.In this particular case the variation of rate with pH has permitted a distinction between a D and la mechanism, a distinction which is usually very difficult to make from kinetic studies of cationic complexes. Another rhodium(iii) complex which is reported to undergo substitution by a D mechanism is the [Rh(ox)3] anion. Examples of chromium(m) complexes which react by a Z) mechanism include [Cr(OH2)5Me]2+, [Cr(OH2)5l] +, [Cr(OH2)5(CN)]2+,and a porphyrin... 

Rate constants and activation parameters for the chloride anation of [Rh(dmgH)2(N02)(0H2)] have been determined from kinetic results obtained for the reversible aquation of the [Rh(dmgH)2(N02)Cl] anion. For the reaction of [Rh(dmgH)2(N02)(0Ha)] with chloride, = 12.0 kcal mol and SS = — 25 cal deg mol. The reported activation enthalpy seems surprisingly low for substitution at rhodium(ra) previously determined activation enthalpies for reactions of complexes of the type [Rh(LL)2(L)(OH2)] with chloride or bromide ions fall within the range 23.8—32.0 kcal mol. ... 

The rate constant for, and extent of, chloride anation at [Pt(bipy) (tach)(OH2)], tach = (79), have been determined in 0.2 mol dm" DCl... 

Kinetic studies of aquation of dinuclear [ traras-PtCl(NH3)2 2 (p-NH2(CH2)6NH2)]2+ established rate constants for the loss of the first and second chloride ligands (7.9 x 10-5 and 10.6 x 10-4s-1), and for the reverse anations (1.2 and 1.5M-1s-1). Reactivities here are very similar to those in analogous mononuclear systems [Pt(amine)3Cl]+ (204). A kinetic and equilibrium study of axial ligand substitution reactions... 

Robb and co-workers have studied the kinetics of the anation of [Rh(H20)Cl5]2 by a variety of monoanions (equation 286 X = Cl, Br, I, N02, N3 or NCS).1213 The rates of anation are relatively independent of the nature of the anating ligand (k 2.9 ( 1) x 10-2s-1 at 35 °C), consistent with a dissociative mechanism. The rates of equilibration of the hexachloro, pentachloro and m-tetra-chloro anions were studied as a function of chloride concentration and the data were fitted to the kinetic expression kobs = + fcanutCl ]- The effect of pressure (1-1500 bar) was also mon-... 

The kinetics and mechanism of the decomposition and anation of trans-[Co(py)4(H20)2] in aqueous acidic chloride solutions has been studied in some detail. Two reactions occur the faster reaction involves replacement of coordinated pyridine by water or chloride ion in parallel pathways, while the slower reaction involves spontaneous reduction of [Co(py)3(H20)2Cl] and [Co(py)3(H20)3] with the chloro complex decomposing at a faster rate than the aqua complex. 

---