Question

Which from following complexes is an example of \(\text{MA}_4\text{BC}\) type distereoisomers ?

• A. \([\text{Pt}(\text{NH}_3)(\text{H}_2\text{O})\,\text{Cl}_2]\)
• B. \([\text{Pt}(\text{NH}_3)_4\,\text{ClBr}]^{2+}\)
• C. \(\text{Pt}(\text{NH}_3)_2\,\text{Cl}_2\)
• D. \([\text{Co}(\text{NH}_3)_4\,\text{Cl}_2]^+\)

Hint:

MA4BC means four identical ligands and two different ligands B and C in an octahedral complex.

Answer 1

The Correct Option is B

Step 1: Understand the notation
In MA4BC, M is the metal, A is a ligand present 4 times, and B and C are two different ligands, each once. The coordination number is 6.

Step 2: Check (B)
\([\text{Pt}(\text{NH}_3)_4\text{ClBr}]^{2+}\) has four \(\text{NH}_3\) (A), one Cl (B) and one Br (C). The coordination number is 6, so it is MA4BC. It can have Cl and Br either adjacent (cis) or opposite (trans), giving geometrical isomers.

Step 3: Check the others
(A) \([\text{Pt}(\text{NH}_3)(\text{H}_2\text{O})\text{Cl}_2]\) has four ligands of three kinds, so it is MABC2 type. (C) \(\text{Pt}(\text{NH}_3)_2\text{Cl}_2\) is MA2B2. (D) \([\text{Co}(\text{NH}_3)_4\text{Cl}_2]^+\) is MA4B2.

Step 4: Conclusion
Only (B) matches MA4BC.

Final Answer:
Four identical ligands plus two different ones fit option (B). This is option (B). \[ \boxed{\text{(B) }[\text{Pt}(\text{NH}_3)_4\text{ClBr}]^{2+}} \]