Question

Lanthanons have weaker tendency to form complexes. Give reason.

Answer 1

They do not form Ln = O or $Ln\equiv N$ multiple bonds of the type known for many transition metals and certain actinides. Unlike the actinides, they do not form stable carbonyls and have (virtually) no chemistry in the 0 oxidation state.The 4f orbitals in the $L{n}^{3+}$ ion do not participate directly in bonding, being well shielded by the $5s^2$ and $5p^6$ orbitals. Their spectroscopic and magnetic properties are thus largely uninfluenced by the ligand.