<P> mer - (CoCl (NH)) </P> <P> Optical isomerism occurs when a molecule is not superimposable with its mirror image . It is so called because the two isomers are each optically active, that is, they rotate the plane of polarized light in opposite directions . The symbol Λ (lambda) is used as a prefix to describe the left - handed propeller twist formed by three bidentate ligands, as shown . Likewise, the symbol Δ (delta) is used as a prefix for the right - handed propeller twist . </P> <Ul> <Li> <P> Λ - (Fe (ox)) </P> </Li> <Li> <P> Δ - (Fe (ox)) </P> </Li> <Li> <P> Λ - cis - (CoCl (en)) </P> </Li> <Li> <P> Δ - cis - (CoCl (en)) </P> </Li> </Ul> <Li> <P> Λ - (Fe (ox)) </P> </Li>

Which of these is an example of the principle of coordination