Question

Which can exist both as diastereoisomer and enantiomer?

• A. $ [P(en)_{3}]^{4+}$
• B. $ [Pt(en)_{2}ClBr]^{2+} $
• C. $ [Ru(NH_{3})_{4}Cl_{2}]^{0}$
• D. $ [PtCl_{2}Br_{2}]^{0} $

Answer 1

Answer: (B)

cis-form of complexes of type $M(A A)_{2} B C$ (example $\left[ Pt ( en )_{2} ClBr \right]^{2+}$ are optically active.
On the other hand transforms are optically inactive due to symmetry. (Unsymmetrical, optically active) and trans- (meso) -form (optically inactive)