Total number of unpaired electrons present in the central metal atoms/ions of [ Ni ( CO )₄ ], [ NiCl ₄ ]²⁻, [ PtCl ₂ ( NH ₃ )₂ ], [ Ni ( CN )₄ ]²⁻ and [ Pt ( CN )₄ ]²⁻ is _ _ _ _ .

Step-by-step solution

[Ni(CO)₄] : Ni is zero-valent with configuration [Ar]3d¹⁰4s^2 . CO is a strong field ligand causing complete pairing in the filled 3d¹⁰ orbital. Unpaired electrons = 0. [NiCl₄]²⁻ : Ni is +2 with configuration [Ar]3d^8 . Cl is a weak field ligand producing high-spin tetrahedral geometry with configuration 3d^8 : five orbitals with two electrons paired, three electrons unpaired. Unpaired electrons = 2. [PtCl₂(NH₃)₂] : Pt is +2 with configuration [Xe]4f¹⁴5d^8 . Pt(II) adopts square planar geometry with strong-field sp