Coordination Compounds Part 2

The coordination compound [

III

Co

(ox)2(Br)(NH3)]2− of general formula [M(A−A)2BC] can show both geometrical and optical isomerism (stereoisomerism). The cis-form produces non-superimposable mirror images, i.e. enantiomeric pairs (optically active)The trans-form is optically inactive.
So, total number of stereoisomers possible
=cis(±)+trans=3