Which of the following octahedral complexes of cobalt exhibits the highest spin-only magnetic moment?

Step-by-step solution

In all the given complexes, cobalt is present in the +3 oxidation state. The electronic configuration of Co ³⁺ is 3 d ^6 . According to the spectrochemical series, CN ^- , en , and NH ₃ act as strong field ligands for the Co ³⁺ ion. They cause pairing of electrons ( _o > P ), resulting in low-spin complexes with an electronic configuration of t _ 2 g ^6 e _ g ^0 . These complexes have 0 unpaired electrons and are diamagnetic (spin-only magnetic moment = 0 ). On the other hand, F ^- is a weak field ligand. It does n