Axial substitution rate constants

Axial substitution rate constants have been determined by Haines and McAuley (25) for anions reacting with nickel(III)-cyclam and some of the constants are given in Table III. The rate constants for the replacement of an axial water molecule by... 

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... 

Nickel(III) peptide complexes have a tetragonally-distorted octahedral geometry as shown by electron spin resonance studies (19) and by reaction entropies for the Ni(III,II) redox couple (17). Axial substitutions for Ni(III)-peptide complexes are very fast with formation rate constants for imidazole greater... 

In nickel(III) peptide complexes, there is a strong in-plane field provided by the deprotonated peptide linkages (117, 118). Two axially coordinated water molecules are present in the tetragonally distorted complexes which exchange much more rapidly than for the [14]aneN4 species with a substitution rate of constant >106 M l sec-1 for the formation of the imidazole complex (141). However, except for the terminal peptide group, equatorial substitution is very slow. Substitution and rearrangement (125) reactions of these species reveal acid-... 

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