Rate constant tabulations complex formation

We can now make sensible guesses as to the order of rate constant for water replacement from coordination complexes of the metals tabulated. (With the formation of fused rings these relationships may no longer apply. Consider, for example, the slow reactions of metal ions with porphyrine derivatives (20) or with tetrasulfonated phthalocyanine, where the rate determining step in the incorporation of metal ion is the dissociation of the pyrrole N-H bond (164).) The reason for many earlier (mostly qualitative) observations on the behavior of complex ions can now be understood. The relative reaction rates of cations with the anion of thenoyltrifluoroacetone (113) and metal-aqua water exchange data from NMR studies (69) are much as expected. The rapid exchange of CN " with Hg(CN)4 2 or Zn(CN)4-2 or the very slow Hg(CN)+, Hg+2 isotopic exchange can be understood, when the dissociative rate constants are estimated. Reactions of the type M+a + L b = ML+(a "b) can be justifiably assumed rapid in the proposed mechanisms for the redox reactions of iron(III) with iodide (47) or thiosulfate (93) ions or when copper(II) reacts with cyanide ions (9). Finally relations between kinetic and thermodynamic parameters are shown by a variety of complex ions since the dissociation rate constant dominates the thermodynamic stability constant of the complex (127). A recently observed linear relation between the rate constant for dissociation of nickel complexes with a variety of pyridine bases and the acidity constant of the base arises from the constancy of the formation rate constant for these complexes (87). 

Chromium(m).—list of activation parameters for complex formation with [Cr(OH2)6l + has been compiled this supplements an earlier tabulation of rate constants for these much-studied reactions. Activation parameters for complex formation with [Cr(OH2)e] and with [Cr(OH2>6-(OH)] + have been compared activation enthalpies are markedly lower for... 

In solution yellow iron(II) species containing one a,a -diimine ligand can be obtained from an excess of Fe + in an acidified solution of the ligand (which controls the amount of available free ligand via protonation). Formation constants for many such complexes of substituted 1,10-phenanthrolines have been reported and tabulated. The rate of formation of [Fe(phen)(H20)4] is rapid and has a very unfavourable entropy of activation ( = 53.6 kJ mol , A5 = — 66.9 J K mor Kinetics of the corresponding reactions with 2,2 -bipyridine have also... 

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