What is the formula of following coordination compound:
Potassium trioxalatoaluminate(III)
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → $K_3[Al(C_2O_4)_3]$
Core Concept:
Oxalate ($C_2O_4^{2-}$) is a bidentate ligand with $-2$ charge. Aluminium is in $+3$ oxidation state.
Stepwise Calculation:
Let charge on complex $= x$
$Al^{3+} + 3(C_2O_4)^{2-}$
$= +3 + 3(-2)$
$= +3 - 6$
$= -3$
So complex ion $= [Al(C_2O_4)_3]^{3-}$.
To neutralise:
$3 K^+$ needed.
Final formula $= K_3[Al(C_2O_4)_3]$.