Question

Which of the following are outer orbital octahedral complexes?
(1) ${\left[Fe{F}_6\right]}^{3-}$
(2) ${\left[Fe(CN{)}_6\right]}^{4-}$
(3) ${\left[Fe{\left(H_{2}O\right)}_6\right]}^{2+}$
(4) ${\left[Fe(CN{)}_6\right]}^{3-}$

• A. 1, 2 and 3 are correct
• B. 1 and 2 are correct
• C. 2 and 4 are correct
• D. 1 and 3 are correct

Answer 1

Answer: (D)

Weak field ligands like $F^{-},H_{2}O$ etc are unable to cause pairing of $d$-electrons of the central metal atom/ion, thus they usually result in the formation of outer orbit complexes (in case metal ion contains atleast $5$ electrons in its d-orbital).
Thus, ${\left[Fe{F}_6\right]}^{3-}$ and ${\left[Fe{\left(H_{2}O\right)}_6\right]}^{2+}$ are outer orbital octahedral complexes.