JEE MAIN - Chemistry (2021 - 20th July Morning Shift - No. 1)
According to the valence bond theory the hybridization of central metal atom is dsp2 for which one of the following compounds?
$$NiC{l_2}.6{H_2}O$$
$${K_2}[Ni{(CN)_4}]$$
$$[Ni{(CO)_4}]$$
$$N{a_2}[NiC{l_4}]$$
Explanation
According to VBT i.e. valence bond theory,
Electronic configuration of Ni = [Ar]3d84s2.
(a) NiCl2 . 6H2O
NiCl2 . 6H2O $$\rightarrow$$ NiCl2 + 6H2O
Oxidation number of Ni(x) = x + 2($$-$$1) = 0; where x, $$-$$1 and 2 are the oxidation number of Ni, oxidation number of Cl and number of Cl atoms respectively.
NiCl2 $$\Rightarrow$$ x + ($$-$$2) = 0 $$\Rightarrow$$ x = 2
Electronic configuration of Ni2+ = [Ar]3d84s0
Cl$$-$$ is a weak field ligand. So, no pairing of electrons occurs.
For C.N. = 6
_20th_July_Morning_Shift_en_1_1.png)
(b) K2[Ni(CN)4]
K2[Ni(CN)4] $$\rightarrow$$ 2K+ + [Ni(CN)4]2$$-$$
x + 4($$-$$1) $$-$$ ($$-$$2) = 0; where x, 4, $$-$$1 and $$-$$2 are the oxidation number of Ni, number of CN ligands, charge on one CN and charge on complex.
[Ni(CN)4]2$$-$$ $$\Rightarrow$$ x $$-$$ 4 + 2 = 0 $$\Rightarrow$$ x = +2
Electronic configuration of Ni2+ $$\Rightarrow$$ [Ar]3d84s0
CN$$-$$ is a strong field ligand. So, pairing of electrons occur. For C.N. = 4
_20th_July_Morning_Shift_en_1_2.png)
(c) Ni(CO)4
CO is neutral and strong field ligand. So, pairing of electrons occur.
Oxidation number of Ni is zero
Electronic configuration of Ni = [Ar]3d104s0
For C.N. = 4
_20th_July_Morning_Shift_en_1_3.png)
(d) Na2[NiCl4]
Na2[NiCl4] $$\rightarrow$$ 2Na + [NiCl4]2$$-$$
x + 4($$-$$1) $$-$$ ($$-$$2) = 0; where x, 4, $$-$$1 and $$-$$2 are the oxidation number of Ni, number of CN ligands, charge on one CN and charge on complex.
[NiCl4]2$$-$$ $$\Rightarrow$$ x $$-$$ 4 + 2 = 0 $$\Rightarrow$$ x = +2
Electronic configuration of Ni2+ = [Ar]3d84s0
For C.N. = 4
_20th_July_Morning_Shift_en_1_4.png)
Hence, only K2[Ni(CN)4] has dsp2 hybridization.
Electronic configuration of Ni = [Ar]3d84s2.
(a) NiCl2 . 6H2O
NiCl2 . 6H2O $$\rightarrow$$ NiCl2 + 6H2O
Oxidation number of Ni(x) = x + 2($$-$$1) = 0; where x, $$-$$1 and 2 are the oxidation number of Ni, oxidation number of Cl and number of Cl atoms respectively.
NiCl2 $$\Rightarrow$$ x + ($$-$$2) = 0 $$\Rightarrow$$ x = 2
Electronic configuration of Ni2+ = [Ar]3d84s0
Cl$$-$$ is a weak field ligand. So, no pairing of electrons occurs.
For C.N. = 6
(b) K2[Ni(CN)4]
K2[Ni(CN)4] $$\rightarrow$$ 2K+ + [Ni(CN)4]2$$-$$
x + 4($$-$$1) $$-$$ ($$-$$2) = 0; where x, 4, $$-$$1 and $$-$$2 are the oxidation number of Ni, number of CN ligands, charge on one CN and charge on complex.
[Ni(CN)4]2$$-$$ $$\Rightarrow$$ x $$-$$ 4 + 2 = 0 $$\Rightarrow$$ x = +2
Electronic configuration of Ni2+ $$\Rightarrow$$ [Ar]3d84s0
CN$$-$$ is a strong field ligand. So, pairing of electrons occur. For C.N. = 4
(c) Ni(CO)4
CO is neutral and strong field ligand. So, pairing of electrons occur.
Oxidation number of Ni is zero
Electronic configuration of Ni = [Ar]3d104s0
For C.N. = 4
(d) Na2[NiCl4]
Na2[NiCl4] $$\rightarrow$$ 2Na + [NiCl4]2$$-$$
x + 4($$-$$1) $$-$$ ($$-$$2) = 0; where x, 4, $$-$$1 and $$-$$2 are the oxidation number of Ni, number of CN ligands, charge on one CN and charge on complex.
[NiCl4]2$$-$$ $$\Rightarrow$$ x $$-$$ 4 + 2 = 0 $$\Rightarrow$$ x = +2
Electronic configuration of Ni2+ = [Ar]3d84s0
For C.N. = 4
Hence, only K2[Ni(CN)4] has dsp2 hybridization.
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