Question

Following valence bond scheme, explain the bonding in [Cr(H₂O)₆]³⁺.

Answer 1

The complex is [Cr(H₂O)₆]³⁺. The electronic configuration is [Ar]4s⁰3d³ . The hybridisation is d²sp³ and no pairing of electrons takes place. 

Therefore, chromium uses its two available 3d orbitals, along with one 4s and three 4p orbitals, to undergo d²sp³ hybridisation. Two d orbitals and three p orbitals take part in bonding. This results in the formation of six equivalent hybrid orbitals, which accept electron pairs from the six water ligands. The resulting geometry of the complex is octahedral. Because there are three unpaired electrons remaining in the 3d orbitals, the complex is paramagnetic in nature.