Question

State the geometry and magnetic property of tetracarbonyl nickel according to the valence bond theory.

Answer 1

1. Tetracarbonyl nickel, Ni(CO)₄, has a tetrahedral geometry.
2. Nickel in Ni(CO)₄ has an atomic number of 28, so its ground-state electronic configuration is:
   Ni (Z = 28): [Ar] 3d⁸ 4s²
3. In the complex, Ni is in the zero oxidation state.
4. The 4s and three 4p orbitals hybridize to form four sp³ hybrid orbitals.
5. In the sp³ hybridization state of the nickel atom within the
   Ni(CO)₄ complex, all the electrons are paired.
6. Each CO ligand donates a lone pair of electrons into these hybrid orbitals.
7. This results in a tetrahedral shape.
8. The 3d electrons in nickel pair up due to the strong field ligand CO.
9. This results in a 3d¹⁰ configuration (fully paired).
10. As there are no unpaired electrons, the complex is diamagnetic.