Question

The co-ordination number of Fe and Co in the complex ions, [F_e(C₂O₄)3]^3- and [Co(SCN)₄]^2- are respectively

• A. 6 and 4
• B. 3 and 4
• C. 6 and 8
• D. 4 and 6

Answer 1

The Correct Option is A

1. For the complex ion [Fe(C\(_2\)O\(_4\))\(_3\)]\(^3-\):
The oxalate ion (C\(_2\)O\(_4\)) is a bidentate ligand, meaning it forms two bonds with the central metal ion.
Since there are 3 oxalate ions in the complex, each forming two bonds with Fe, the total coordination number of Fe is \( 3 \times 2 = 6 \).
2. For the complex ion [Co(SCN)\(_4\)]\(^2-\):
The thiocyanate ion (SCN\(^-\)) is a monodentate ligand, meaning it forms only one bond with the central metal ion.
Since there are 4 SCN\(^-\) ions in the complex, the coordination number of Co is 4.
Thus, the coordination numbers are: Fe: 6, Co: 4

The correct option is (A): 6 and 4

Answer 2

[Fe(C\(_2\)O\(_4\))\(_3\)]\(^{3-}\): In this complex, oxalate (\(C_2O_4^{2-}\)) acts as a bidentate ligand, meaning it forms two bonds with the metal ion. Since there are three oxalate ligands, the total coordination number of Fe in this complex is \(3 \times 2 = 6\). Therefore, the coordination number of Fe is 6.
 
[Co(SCN)\(_4\)]\(^{2-}\): Here, thiocyanate (SCN\(^-\)) acts as a monodentate ligand, forming one bond with the Co ion. Since there are four thiocyanate ligands, the coordination number of Co in this complex is 4.

Thus, the coordination numbers of Fe and Co are 6 and 4, respectively.