Chemistry - Coordination Chemistry Question with Solution | TestHub

In case of strong field ligand containing complexes, electrons get pair up against the Hund's rule to get required number of hybrid orbitals. Among the given complexes' ammonia is a strong-filed ligand and other ligands are weak filed ligands. ${\left[\mathrm{Co}{\left({\mathrm{NH}}_3\right)}_6\right]}^{3+}$ has $\mathrm{d}{ }^2{\mathrm{sp}}^3$ (inner orbital complex) with zero unpaired electrons. Hence, it is octahedral with diamagnetic character and low spin complex. ${\left[{\mathrm{CoF}}_6\right]}^{3–}$ and ${\left[{\mathrm{CoCl}}_6\right]}^{3–}$ are octahedral but having unpaired electrons.${\left[{\mathrm{NiCl}}_4\right]}^{2-}$ is not octahedral.