Question

what type of bond (like covalent,co-ordinate,eletrovalent) present in K4[Fe(cn)6],and why?

Answer 1

What type of bond (like covalent, coordinate, ionic) is present in $\mathrm{K}_4[\mathrm{Fe}(\mathrm{CN})_6]$ and why?

Answer: In the molecule of $\mathrm{K}_4[\mathrm{Fe}(\mathrm{CN})_6]$ all three types of bonds mentioned above are present.

Covalent bonds are in the cyanide ions between the atoms of carbon and nitrogen which have medium difference in electronegativities: $\mathsf{N} \equiv \mathsf{C}^{-}$ . Coordinate bonds are between the central atom of iron and surrounding cyanide ions; iron has free electron orbitals, and carbon of the cyanide ion has a pair of valent electrons which are forming together the coordinate bond: $\mathsf{N} \equiv \mathsf{C}^{-} \rightarrow \square \mathsf{Fe}^{2+}$ . And ionic (electrovalent) bonds are between outer potassium ions $\mathsf{K}^{+}$ and complex ferrocyanide ion $[\mathsf{Fe}(\mathsf{CN})_{6}]^{4-}$ , because they have a large difference in the electronegativities of potassium and carbon.

Molecular structure of the potassium ferrocyanide can be shown as: