Why do the metals Co, Rh, and Lr form octahedral complexes (rather than tetrahedral or square planar complexes) ? Hint: Look at the placement in the periodic table and the respective electron configurations.

Octahedral complexes will be favoured over tetrahedral ones because:

It is more favourable to form six bonds rather than four

The crystal field stabilisation energy is usually greater for octahedral than tetrahedral complexes.

The transition metals Co, Rh, Lr are in group 9 of d block and they have 3d, 4d, and 5d orbitals respectively