# Why member ring is favoured in chelates?

why chelates which form 3 or 4 member rings or 6 or 7 member rings are as stable as 5 member ring chelates? for example if we measure stability of chelates with oxygen donors, say oxalate, malonate, succinate etc oxalate chelated with metal shoes more stability. why malonate , succinate as chelating ligands are less stable?

• Chelating increases the stability , probably due to more change in positive entropy – Heisenberg Mar 19 '15 at 7:03

## 1 Answer

In its general form, your statement on the stability of these complexes is wrong!

$\ce{Be(II)}$-malonato complexes are more stable than the corresponding oxalato complexes, cf. Preparative, potentiometric and NMR studies of the interaction of beryllium(II) with oxalate and malonate.

• no sir i was not trying to say it was universal, i saw in books that said 5 member ring forming chelates are relatively more stable than 6 member or 7 member or 4 member ring forming chelates. – Punarbasu Roy Mar 19 '15 at 14:14