In [M(a)3(b)3] why mer-isomer do not show optical isomerism?
Consider the octahedral compound FeCl3F3 of the form [M(a)3(b)3] with Fe as central metal atom
(note the color scheme: orange=iron, blue=fluorine, green=chlorine):
we try to attempt this problem using the mirror image method, we notice that the mirror image is essentially identical to the original molecule. In other words, the mirror image can be placed on top of the original molecule and is thus superimposable. Since the mirror image is superimposable, this molecule does not have any optical isomers. Let's attempt this same problem using the symmetry method. If we draw an axis or plane of symmetry, this is what we get:
Since the left side is identical to the right side, this molecule has a symmetrical center and is an achiral molecule. Thus, it has no optical isomers.
Consider the octahedral compound FeCl3F3 of the form [M(a)3(b)3] with Fe as central metal atom
(note the color scheme: orange=iron, blue=fluorine, green=chlorine):
we try to attempt this problem using the mirror image method, we notice that the mirror image is essentially identical to the original molecule. In other words, the mirror image can be placed on top of the original molecule and is thus superimposable. Since the mirror image is superimposable, this molecule does not have any optical isomers. Let's attempt this same problem using the symmetry method. If we draw an axis or plane of symmetry, this is what we get:
Since the left side is identical to the right side, this molecule has a symmetrical center and is an achiral molecule. Thus, it has no optical isomers.
