Dentates

[Rhea Palsule]

When determining if a molecule is monodentate or polydentate, do you simply look at the number of lone electron pairs? Or should you also take formal charge into account? For example oxygen with 2 lone pairs and 2 bonds has a formal charge of 0 but 2 lone pairs. Does that mean it is polydentate or monodentate?

[Jasmine Holloway 1G]

You want to look at the amount to atoms with lone pairs to determine if it is polydentate. Atoms will not form more than one bond to the TM even if it has more than one lone pair. Oxygen has a formal charge of 0 when it has a double bond so therefore it won't form a bond to a TM.