The correct order of $\left[\mathrm{FeF}_6\right]^{3-},\left[\mathrm{CoF}_6\right]^{3-}…

The correct order of $\left[\mathrm{FeF}_6\right]^{3-},\left[\mathrm{CoF}_6\right]^{3-},\left[\mathrm{Ni}(\mathrm{CO})_4\right]$ and $\left[\mathrm{Ni}(\mathrm{CN})_4\right]^{2-}$ complex species based on the number of unpaired electrons present is :
  1. $\left[\mathrm{FeF}_6\right]^{3-} \gt \left[\mathrm{CoF}_6\right]^{3-} \gt \left[\mathrm{Ni}(\mathrm{CN})_4\right]^{2-} \gt \left[\mathrm{Ni}(\mathrm{CO})_4\right]$
  2. $\left[\mathrm{Ni}(\mathrm{CN})_4\right]^{2-} \gt \left[\mathrm{FeF}_6\right]^{3-} \gt \left[\mathrm{CoF}_6\right]^{3-} \gt \left[\mathrm{Ni}(\mathrm{CO})_4\right]$
  3. $\left[\mathrm{CoF}_6\right]^{3-} \gt \left[\mathrm{FeF}_6\right]^{3-} \gt \left[\mathrm{Ni}(\mathrm{CO})_4\right] \gt \left[\mathrm{Ni}(\mathrm{CN})_4\right]^{2-}$
  4. $\left[\mathrm{FeF}_6\right]^{3-} \gt \left[\mathrm{CoF}_6\right]^{3-} \gt \left[\mathrm{Ni}(\mathrm{CN})_4\right]^{2-}=\left[\mathrm{Ni}(\mathrm{CO})_4\right]$

Asked in: JEE Main 2025 (04 Apr Shift 2)

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