Question

Excitation-transfer theory by zillmann?

Answer 1

According to valence bond theory , The hybrid orbitals are more stable than atomic orbitals, and participate in bond formation. The VB theory and concept of Hybridisation can also be applied to co-ordination compounds. For hybridizations in central atom the electrons are transferred form filled orbital to vacant orbital as shown below in case of carbon.
 

But in case of coordination compound the hybridised orbitals are allowed to overlap with ligand orbitals that can donate electron pairs for bonding. So, the orbital in metal is needed to be empty by transferring the electrons. In most of cases electron transfer is adjusted in d-orbitals or suitable number of electrons are being removed in formation of metal cations. Look at the following examples :




Orbitals are vacated by formation of cation only.




Orbitals are vacated for hybridizations by transferring the electrons in already filled d-orbital.