Cobalt, tris optical isomerism

Cobalt, tris(tetraaminine-p-dihydroxocobalt)-optical isomerism, 1,13... 

It must be concluded, therefore, that the ligands do not become completely detached from the metal ion in isomerization reactions. Comparable results have been observed in the isomerization95 of potassium diaquodioxalatochromium(III) and the racemization96 of optically active potassium tris(oxalato)chromium(III) when no exchange with free ligand in solution occurs. Thus, although it is not practicable to take advantage of the desirable properties of individual isomers of 2 1 chromium and cobalt complexes of tridentate azo compounds because of the facility with which such compounds isomerize in solution, the technically important unsymmetrical 2 1 complexes are capable of practical application because they show little or no tendency to disproportionate in solution. 

The optical isomers of cis-Cr(benz)3 are quite stable in dry chloroform in the dark, yet isomerize rapidly in methanolic solution. The trans-isomer is moderately stable in alcohols, with a half-life for racemization of a few days. Due to the instability with respect to decomposition of the neutral tris(benzohydrox-amato)cobalt(III) complex, only the CD spectrum of the anionic species has been recorded (Figure 7). It resembles that of the cis-Cr(hydroxamate)3 complexes. 

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