Question

The complex $[CoF_{6}]^{4-}$ is

• A. outer orbital and diamagnetic
• B. inner orbital and paramagnetic
• C. inner orbital and diamagnetic
• D. outer orbital and paramagnetic

Answer 1

Answer: (D)

outer orbital and paramagnetic

Answer 2

In $\left[ CoF _{6}\right]^{4-}$, central metal Co is present as $Co ^{2+}$. $C o^{2+}=[A r] 3 d^{7} 4 s^{0}$ Because of the presence of three unpaired electrons, the complex is paramagnetic. Moreover, $F^-$ ions occupy outer $d$-orbitals (ie, $nd$-orbitals), thus it is an outer orbital complex.