JEE Main 2026 — Chemistry Inorganic Chemistry

In $[Ni(PPh_3)_2Cl_2]$[Ni(PPh3​)2​Cl2​], Nickel is in $+2$+2 oxidation state. $Ni^{2+}$Ni2+ has a $3d^8$3d8 electronic configuration.

The complex is given as paramagnetic. For a 4-coordinate $d^8$d8 system, paramagnetism implies a tetrahedral geometry ($sp^3$sp3 hybridization) with two unpaired electrons.

Statement A: Tetrahedral complexes of the type $[MA_2B_2]$[MA2​B2​] do not exhibit geometrical isomerism because all positions are adjacent to each other. Thus, A is incorrect.

Statement B: Most $Ni(II)$Ni(II) complexes are colored due to $d-d$d−d transitions. $[Ni(PPh_3)_2Cl_2]$[Ni(PPh3​)2​Cl2​] is a dark blue/green crystalline solid, not white. Thus, B is incorrect.

Statement C: With 2 unpaired electrons, the spin-only magnetic moment $\mu = \sqrt{n(n+2)} = \sqrt{2(2+2)} = \sqrt{8} \approx 2.83$μ=n(n+2)​=2(2+2)​=8​≈2.83 BM. Thus, C is correct.

Statement D: For a tetrahedral complex with $d^8$d8 configuration, the CFSE is calculated as $CFSE = [(-0.6 \times 4) + (0.4 \times 4)]\Delta_t = -0.8\Delta_t$CFSE=[(−0.6×4)+(0.4×4)]Δt​=−0.8Δt​. The statement mentions $-0.8\Delta_o$−0.8Δo​, which is incorrect as the complex is tetrahedral, not octahedral. Thus, D is incorrect.

Statement E: $Ni(CO)_4$Ni(CO)4​ is a tetrahedral complex ($sp^3$sp3 hybridization). Since $[Ni(PPh_3)_2Cl_2]$[Ni(PPh3​)2​Cl2​] is also tetrahedral, their geometrical arrangements are similar. Thus, E is correct.

The incorrect statements are A, B, and D.