Question

The Co-ordination number of $Fe$ and $Co$ in the complex ions, $Fe(C_2{O}_4{)}_3{]}^{3-}$ and $[Co(SCN{)}_4{]}^{2-}$ are respectively:

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

Answer 1

Answer: (D)

$C_2{O}_4^{2-}$ is the oxalate ligand. It binds through two oxygen atoms and thus, is a bidentate ligand.

Hence the co-ordination number of $Fe$ in ${\left[Fe{\left(C_2{O}_4\right)}_3\right]}^{3-}$ is $6$ .

$SC{N}^{-}$ is the thiocyanate ligand. It is a monodentate ligand. Hence the co-ordination number of

$Co$ in the complex ion ${\left[Co(SCN{)}_4\right]}^{2-}$ is $4$ .