Question

Which among the following is NOT an octahedral complex?

• A. \([\mathrm{Ir(C_2O_4)_2Cl_2}]^{3-}\)
• B. \([\mathrm{CoCl_2(en)_2}]^+\)
• C. \([\mathrm{Co(en)_2(NO_3)_2}]^+\)
• D. \([\mathrm{Pt(NH_3)_2Cl_2}]\)

Hint:

Platinum(II) complexes commonly show square planar geometry.

Answer 1

The Correct Option is D

Step 1: Understanding octahedral geometry.
An octahedral complex has coordination number 6, meaning six ligand donor atoms are attached to the central metal ion.

Step 2: Checking coordination numbers.
Options (A), (B), and (C) all have six donor atoms around the metal ion, leading to octahedral geometry.

Step 3: Analyzing option (D).
\([\mathrm{Pt(NH_3)_2Cl_2}]\) has coordination number 4 and forms a square planar complex, not octahedral.

Step 4: Conclusion.
Hence, \([\mathrm{Pt(NH_3)_2Cl_2}]\) is NOT an octahedral complex.