Chemistry - Coordination Chemistry Question with Solution | TestHub

$aca{c}^{-}$ (acetylacetonate) forms a 6-membered chelate ring consisting of the atom sequence $M-O-C-CH-C-O$.

$tn$ (1,3-diaminopropane) also forms a 6-membered chelate ring consisting of the sequence $M-N-C-C-C-N$.

The remaining ligands (bn, dipy, edta${}^{4-}$, o-phen, and dien) contain shorter pathways between donor atoms and only form 5-membered rings.

Thus, only 2 ligands ($aca{c}^{-}$ and $tn$) form six-membered rings with the central metal ion.