JEE Main 2022 · Chemistry · Coordination Compounds · hard

Among [Ni(CN)4]^2-, [NiCl4]^2-, Ni(CO)4, [Fe(CN)6]^3-, [Co(NH3)6]^3+ and [CoF6]^3-, the number of complexes that are diamagnetic and also use the…

Numerical answer

Among

\mathrm{[Ni(CN)_4]^{2-}}

\mathrm{[NiCl_4]^{2-}}

\mathrm{Ni(CO)_4}

\mathrm{[Fe(CN)_6]^{3-}}

\mathrm{[Co(NH_3)_6]^{3+}}

and

\mathrm{[CoF_6]^{3-}}

, the number of complexes that are diamagnetic and also use the

(n-1)d

orbitals in hybridisation is

Show answer and solution

Answer: 2

\mathrm{[Ni(CN)_4]^{2-}}

\mathrm{Ni^{2+}}

d^8

, strong field pairing,

dsp^2

square planar, diamagnetic and uses

3d

: counts.

\mathrm{[NiCl_4]^{2-}}

sp^3

, two unpaired electrons: no.

\mathrm{Ni(CO)_4}

: Ni(0)

3d^{10}

sp^3

, diamagnetic but no

d

orbital used: no.

\mathrm{[Fe(CN)_6]^{3-}}

d^2sp^3

but one unpaired electron: no.

\mathrm{[Co(NH_3)_6]^{3+}}

\mathrm{Co^{3+}}

d^6

low spin,

d^2sp^3

, diamagnetic: counts.

\mathrm{[CoF_6]^{3-}}

sp^3d^2

, four unpaired electrons: no. Answer 2.

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