Exchange of Central Metal Atom

Recent kinetic studies of metal ion exchanges include those of europium(iii) with its cydta complex and of various lanthanides(iii) with their respective dtpa complexes. Kinetic studies of metal ion replacement include reactions of nta, edda, heedta, egta, cydta, and dtpa complexes of zinc(ii) with copper(ii), of edta nedta, cydta, and dtpa complexes of lead(ii) with cobalt(ii), of the edta complex of nickel(ii) with indium(iii), and of ttha complexes of cadmium(ii) with lanthanides(in). There are again several systems mainly concerned with 3 + and 4+ ions, for example those involving edta and dtpa complexes of lanthanides. In systems containing ions of high charge, it seems to be easier to demonstrate the existence of dinuclear intermediates of the type invoked in associative (cf. above) pathways. 

Takahashi, Fukushima Kogyo Koto Semmon Gakko Kiyo, 1976, 39 Chem, Abs, 1978, 89, 169 784). 

Three studies involving intramolecular linkage isomerizations of the unidentate NOa , NCS , and MeCOa ions have appeared.  

Reaction of [Co(NH3)5( OH)] + ion with acetyl perchlorate in trimethyl phosphate solution gives [Co(NH3)5( OCOMe)] + ion. However, in more polar solvents isomerization to the [Co(NH3)5(OC OMe)] ion occurs, and during purification (by recrystallization) it is necessary to avoid polar solvents like HjO to prevent the linkage isomerization. At room temperature 32% rearrangement occurs in the solid phase after 90 days.  

Activation parameters, AF=, A/f, and AA for the isomerization of trans-[Co(en)2(OCOMe)(OHa)] + ion under different conditions are collected in Table 1. Previous high-pressure studies of the transcis isomerizations of 

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