Question
Explain as to how the two complexes of nickel, [Ni(CN)4]2– and Ni(CO)4, have different structures but do not differ in their magnetic behaviour (Ni = 28).
Solution
(i) [Ni(CN)4]2–: In case the valence shell electronic configuration of ground state Ni atom is 3d8 4s2. There is Ni2+ ion for which the electronic configuration in the valence shell is 3d8 4s0.
In presence of strong field CN- ions, all the electrons are paired up. The empty 4d, 3s and two 4p orbitals undergo dsp2 hybridization to make bonds with CN- ligands in square planar geometry
(ii) Ni(CO)4 : In case the valence shell electronic configuration of ground state Ni atom is 3d8 4s2. All of these 10 electrons are pushed into 3d orbitals and get paired up when strong field CO ligands approach Ni atom. The empty 4s and three 4p orbitals undergo sp3 hybridization and form bonds with CO ligands to give tetrahedral
In presence of strong field CN- ions, all the electrons are paired up. The empty 4d, 3s and two 4p orbitals undergo dsp2 hybridization to make bonds with CN- ligands in square planar geometry
(ii) Ni(CO)4 : In case the valence shell electronic configuration of ground state Ni atom is 3d8 4s2. All of these 10 electrons are pushed into 3d orbitals and get paired up when strong field CO ligands approach Ni atom. The empty 4s and three 4p orbitals undergo sp3 hybridization and form bonds with CO ligands to give tetrahedral
