Geometrical shapes of the complexes formed by the reaction of Ni2+ with Cl¯ , CN¯ and H2O, respectively are
Complexes are : [NiCl4]–2, [Ni(CN)4]–2 & [Ni(H2O)6]+2
Ni+2 = 3d84s0
[NiCl4]–2 : Now Since, Cl– is a weak legand so no pairing of electron take place and geometry is tetrahedral
[Ni(CN)4]–2 : Since, CN– is a strong legand so pairing of electron will take place & geometry is square planar.
[Ni(H2O)6]+2 : It will formed octahedral complex since C.N. = 6
The geometry of coordination complexes depends on the coordination number and the nature of ligands. For Ni2+ (d8 configuration), the geometry is influenced by ligand field strength.
Step 1: Reaction with Cl–
Cl– is a weak field ligand. Ni2+ forms [NiCl4]2– with coordination number 4. Weak field ligands do not cause pairing, leading to tetrahedral geometry to minimize repulsion.
Step 2: Reaction with CN–
CN– is a strong field ligand. It causes pairing of electrons in Ni2+ (d8). Ni2+ forms [Ni(CN)4]2– with coordination number 4. Strong field and square planar geometry is stabilized for d8 ions, so it is square planar.
Step 3: Reaction with H2O
H2O is a weak field ligand. Ni2+ forms [Ni(H2O)6]2+ with coordination number 6. Weak field ligands do not pair electrons, and octahedral geometry is common for coordination number 6, so it is octahedral.
Final Answer: The geometries are tetrahedral with Cl–, square planar with CN–, and octahedral with H2O. So, the correct option is: tetrahedral, square planar and octahedral.
Valence Bond Theory (VBT): Explains geometry based on hybridization. For tetrahedral: sp3, square planar: dsp2, octahedral: sp3d2 or d2sp3.
Crystal Field Theory (CFT): Strong field ligands cause large splitting (Δo), leading to electron pairing and square planar geometry for d8 ions. Weak field ligands cause small splitting, favoring high spin complexes and tetrahedral/octahedral geometries.
Key Formula: Coordination number and ligand strength determine geometry. No specific mathematical formula, but understanding of d-orbital splitting and electron configuration is crucial.