Cobalt complexes stereoisomerism

The effects of geometric and ligand stereoisomerism on Co shielding are reported for a series of tris(bidentate)cobalt complexes involving chiral and achiral -diketones. (231) Owing to the broad lines in some of the asymmetrically coordinated systems separate resonances are not always resolved. 

Pt(NH3)2Cl2], for example, the chloro ligands can be either adjacent to or opposite each other ( Figure 23.21). (We saw an earlier example of this type of isomerism in the cobalt complex of Figure 23.8, and we will return to that complex in a moment.) This form of stereoisomerism, in which the arrangement of the atoms is different but the same bonds are present, is called geometric isomerism. The isomer on the left in... 

Cobaltacyclobutene 39 reacts with alkynes in a net insertion/reductive elimination process to yield stereoisomeric cobalt-77-cyclopentadiene complexes 55 (Equation 17) <1995JA8029>. 

One of the earliest cases of stereoisomerism among inner complexes, tris(glycinato)cobalt(III), occurs in two forms, violet (a) and red (P). In one of these geometric isomers, all of the amino groups of the glycine molecules are adjacent (fac), while in the other, two of these occupy opposite positions mer). Absorption spectra indicate that the more soluble violet a form is the mer isomer. " ... 

The stereoisomerism and equilibrium properties of dioxygen carrying cobalt(II) complexes of histamine and its derivatives have recently been reinvestigated. ... 

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