Coordination Compounds
5.0 Valence bond theory
5.0 Valence bond theory
According to Valence bond theory, ligand form coordinate bond with vacant orbital of central metal/ion having same energy level. Thus pure orbitals equalize their energy through process of intermixing of orbitals known as Hybridisation.
According to this theory shape, hybridisation, geometry, magnetic behaviour of complex compound depends upon nature of ligand. When ligand are arranged in increasing order of their splitting power, a series is obtained called Spectro chemical series.
Splitting of $d$-shells:
${I^ - } < B{r^ - } < {S^{2 - }} < SC{N^ - } < C{l^ - } < N{O_3}^ - < {F^ - } < {H_2}O = {C_2}{O_4}^ - < C{H_3}C{O^ - } < NC{S^ - } < N{H_3} = py < en < dipy < C{N^ - } < CO$
If a ligand is strong base, then it is a strong ligand.
Order of Basicity:
${X^ - }({\text{Halogen)}} < O({\text{donor atom}}) < N({\text{donor atom}}) < C({\text{donor atom}})$
- ${F^ - } > {I^ - }{\text{ (base) as }}HI > HF{\text{ (acid)}}$
