The nature of bonding, structure of the coordination compound can be explained to
some extent by valence bond theory. The central metal atom/ion makes available a num
ber of vacant orbitals equal to its coordination number. The appropriate atomic orbitals
(s, p and d) of the metal hybridize to give a set of equivalent orbitals of definite geome
try such as square planar, tetrahedral, octahedral and so on. A strong covalent bond is
formed only when the orbitals overlap to the maximum extent. The d-orbitals involved
in the hybridization may be either inner d-orbitals i.e. (n–1) d or outer d-orbitals i.e. nd.
The complexes formed are called inner orbital complex (low spin complex) and outer
orbital complex (high spin complex) respectively. Further, the complexes can be para
magnetic or diamagnetic in nature. The drawbacks of this theory are that this involves
number of assumptions and also does not explain the colour of the complex.
Answer the following questions: