Which compound have electrovalent, covalent, coordinate as well as hydrogen bond ?

A) $\ce{[Cu(H2O)4]SO4.H2O}$
B) $\ce{[Zn(H2O)6]SO4.H2O}$
C) $\ce{[Fe(H2O)6]SO4.H2O}$
D) $\ce{[Fe(H2O)6]Cl3}$

Answer given:

Option (A)

My approach

All the compounds contain electrovalent, covalent as well as coordinate bonds hence the deciding factor is hydrogen bonding. (D) clearly would not have hydrogen bonding. I know that in (A) which is $\ce{CuSO_4.5H_2O}$ the fifth $\ce{H_2O}$ which is something that was taught to me earlier.

My Doubt:
Yes I get the answer to the given mcq problem above but I was not able to understand the case of (B) and (C). I think that the $\ce{H_2O}$ inside the coordination sphere are bonded through dative bond and the $\ce{SO_4}$ outside by ionic bonds but I am not able to understand the nature of bond formed by "$\ce{.H_2O}$" present outside the main coordination sphere given in the complexes above. Would they not form hydrogen bond? The answer scheme doesn't think so. So if they don't what is the nature of bond formed by these "$\ce{.H_2O"}$ !?

  • $\begingroup$ Edited the question. Please let me know if any further clarifications are required. $\endgroup$
    – Ashish
    Commented Jun 15, 2021 at 4:11

1 Answer 1


All compounds have electrovalent bonds between the metal and the anion (sulfate or chloride). All have covalent bonds between O and H in the water molecules. All have coordinate bonds with water around the metal. And A, B, and C have hydrogen bonds between the inner and the outer water molecules.


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