COMEDK · Chemistry · 24. Coordination Compounds

Among the complexes of Ni listed below, the following is the only correct statement about the given compounds.
I. \(\left[\mathrm{Ni}(\mathrm{CO})_{4}\right]\)
II. \(\left[\mathrm{Ni}(\mathrm{CN})_{4}\right]^{2-}\)
III. \(\left[\mathrm{NiCl}_{4}\right]^{2-}\)

A all of them have tetrahedral geometry.
B I and III are tetrahedral and II has square planar geometry.
C I and II are tetrahedral and III is square planar.
D all of them have square planar geometry.

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Answer & Solution

Correct Answer

(B) I and III are tetrahedral and II has square planar geometry.

Step-by-step Solution

Detailed explanation

\({ }_{28} \mathrm{Ni}=3 d^{8} 4 s^{2}\) In \(\left[\mathrm{Ni}(\mathrm{CO})_{4}\right], \mathrm{CO}\) is a strong field ligand which causes pairing of electrons. In \(\left[\mathrm{Ni}(\mathrm{CN})_{4}\right]^{2-}, \mathrm{CN}^{-}\)is a strong field ligand which causes pairing…

Apply the relevant identity from the chapter and substitute the values established in the previous step, keeping the original constraint in view.

Use the simplified expression to isolate the unknown, then plug the result back into the question setup to confirm the working is internally consistent.

Cross-check against a boundary or limiting case. Both the dimensional balance and the qualitative behaviour at the extreme should agree with the candidate answer.

Combine the steps above to identify the correct option. The remaining choices each fail at least one of the consistency, dimensional, or boundary checks.

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Match the Coordination compounds in Column I with the type of stereoisomerism given in Column II exhibited by them.

Column I	Column II
A. \([\text{Pt}(\text{NH}_3)_2\text{Cl}_2]\)	P. fac-mer
B. \(\text{Ni}[(\text{NH}_3)_2\text{Cl}_2]\)	Q. cis-trans
C. \([\text{Co}(\text{NH}_3)_3(\text{NO}_2)_3]\)	R. only cis isomer shows optical isomerism
D. \([\text{Pt}\,\text{Cl}_2(\text{en})_2]^{2+}\)	S. does not exhibit isomerism.

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Among the complexes of Ni listed below, the following is the only correct statement about the given compounds.I. \(\left[\mathrm{Ni}(\mathrm{CO})_{4}\right]\)II. \(\left[\mathrm{Ni}(\mathrm{CN})_{4}\right]^{2-}\)III. \(\left[\mathrm{NiCl}_{4}\right]^{2-}\)

Step-by-step Solution

Among the complexes of Ni listed below, the following is the only correct statement about the given compounds.
I. \(\left[\mathrm{Ni}(\mathrm{CO})_{4}\right]\)
II. \(\left[\mathrm{Ni}(\mathrm{CN})_{4}\right]^{2-}\)
III. \(\left[\mathrm{NiCl}_{4}\right]^{2-}\)