Why is the complex `[CoF_6]^(3-)` less stable than the complex `[Co(en)_3]^(3+)` ?

Explanation

In the complex `[Co(en)_(3)]^(3+)`, the ligands `en` are cheating ligands while in the complex `[CoF_(6)]^(3-)`, the ligands `F^(-)` ions are monodentate in nature. The chelating ligands impart extra stability to the complex.