question_answer

The complex \[{{[Co{{F}_{6}}]}^{4-}}\] is

A)  outer orbital and diamagnetic

B)  inner orbital and paramagnetic

C)  inner orbital and diamagnetic

D)  outer orbital and paramagnetic

Correct Answer: D

Solution :

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