Which of the following outer octahedral complexes have same number of unpaired electrons? 1.…
Which of the following outer octahedral complexes have same number of unpaired electrons?
1. \(\left[\mathrm{MnCl}_6\right]^{3-}\)
2. \(\left[\mathrm{FeF}_6\right]^{3-}\)
3. \(\left[\mathrm{CoF}_6\right]^{3-}\)
4. \(\left[\mathrm{Ni}\left(\mathrm{NH}_3\right)_6\right]^{2+}\)
1 and 3
1 and 2
3 and 4
2 and 3
Solution
All four complexes given are outer orbital or high spin octahedral complexes. So, \(d\)-orbital electrons of central metal ions of the complexes remain unaffected by weak field ligands.
So, \(d\)-configuration of free \(M^{n+}\) and coordinated \(M^{n+}\) will remain same.
1.
1. \(\left[\mathrm{Mn} \mathrm{Cl}_6\right]^{3-} \longrightarrow \mathrm{Mn}^{3+} \Rightarrow d^4, n=4\)
[ \(\because n=\) Number of unpaired electrons]
2. \(\left[\mathrm{FeF}_6\right]^{3-} \longrightarrow \mathrm{Fe}^{3+} \Rightarrow d^5, n=5\)
3. \(\left[\mathrm{CoF}_6\right]^{3-} \longrightarrow \mathrm{Co}^{3+} \Rightarrow d^6, n=4\)
4. \(\left[\mathrm{Ni}\left(\mathrm{NH}_3\right)_6\right]^{2+} \longrightarrow \mathrm{Ni}^{2+} \Rightarrow d^3, n=2\)
So, complexes 1 and 3 have same number of unpaired electrons \((n=4)\).