Discuss the $[NiCl_4]^{2-}$ complex species based on Valence Bond Theory.

(N/A) In the $[NiCl_4]^{2-}$ complex,the oxidation state of $Ni$ is $+2$. The electronic configuration of $Ni^{2+}$ is $[Ar] 3d^8$.
Since $Cl^-$ is a weak field ligand,it does not cause pairing of electrons in the $3d$ orbitals. Therefore,the $3d$ electrons remain unpaired.
To accommodate four $Cl^-$ ligands,one $4s$ and three $4p$ orbitals undergo $sp^3$ hybridization,resulting in four equivalent $sp^3$ hybrid orbitals directed towards the corners of a tetrahedron.
Four pairs of electrons from four $Cl^-$ ions are donated into these four $sp^3$ hybrid orbitals. Thus,the complex has a tetrahedral geometry.
Due to the presence of two unpaired electrons in the $3d$ orbitals,the complex is paramagnetic.