Coordination Compounds 2 Question 14
16. The coordination number of Th in $K _4\left[Th\left(C _2 O _4\right) _4\left(OH _2\right) _2\right]$ is $\left(C _2 O _4^{2-}=\right.$ Oxalato $)$
(2019 Main, 11 Jan II)
(a) $14$
(b) $10$
(c) $ 8$
(d) $ 6$
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Answer:
Correct Answer: 16. (b)
Solution:
- Coordination number is defined as the total number of ligands to which the metal is directly attached.
Here, $C _2 O _4^{2-}$ is a bidentate ligand,

and $H _2 O$ is a monodentate ligand, $H _2 \stackrel{..}O: \longrightarrow M$
So, total number of sites offered by $C _2 O _4^{2-}$ and $H _2 O$ ligands around $Th(IV)=$ Coordination number of Th (IV)
$ =4 \times 2\left(\text { by } C _2 O _4^{2-}\right)+2 \times 1\left(\text { by } H _2 O\right)=10 $