Match List-I with List-II.
List-I (Complex)List-II (Hybridisation of central metal ion)
(A) [CoF_6]^3-(I) d^2sp^3
(B) [NiCl_4]^2-(II) sp^3
(C) [Co(NH_3)_6]^3+(III) sp^3d^2
(D) [Ni(CN)_4]^2-(IV) dsp^2
Choose the correct answer from the options given below :

Solution & Explanation

### Related Formula Coordination Number 6 corresponds to either d^2sp^3 or sp^3d^2 configuration templates. Coordination Number 4 corresponds to either sp^3 or dsp^2 configuration templates. ### Core Logic Analyzing metal orbital dynamics under varying ligand fields: - **(A) [CoF_6]^3-**: Co^3+ (3d^6) with a weak field ligand (F^-) rightarrow no pairing occurs rightarrow utilizes outer orbitals rightarrow sp^3d^2. - **(B) [NiCl_4]^2-**: Ni^2+ (3d^8) with a weak field ligand (Cl^-) rightarrow no pairing occurs rightarrow tetrahedral profile rightarrow sp^3. - **(C) [Co(NH_3)_6]^3+**: Co^3+ (3d^6) with a strong field ligand (NH_3) rightarrow electrons pair up rightarrow inner orbital configuration rightarrow d^2sp^3. - **(D) [Ni(CN)_4]^2-**: Ni^2+ (3d^8) with a strong field ligand (CN^-) rightarrow forced pairing opens a 3d slot rightarrow square planar geometry rightarrow dsp^2. ### Step 1: Final Pairing Match The completed matching configuration aligns cleanly with: (A)-(III), (B)-(II), (C)-(I), (D)-(IV). ### Pattern Recognition Isolate coordination frameworks quickly: - Nickel(II) with weak field ligands (Cl^-) yields sp^3, while with strong field ligands (CN^-) it yields dsp^2. - Cobalt(III) with weak field ligands (F^-) yields sp^3d^2, while with strong field ligands (NH_3) it yields d^2sp^3. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 12 Chemistry: Coordination Compounds

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Coordination Compounds

More Coordination Compounds Previous-Year Questions — Page 8

Q67 jee_main_2024_01_february_morning Colour in Coordination Compounds
Given below are two statements: Statement (I): A solution of [Ni(H_2O)_6]^2+ is green in colour. Statement (II): A solution of [Ni(CN)_4]^2- is colourless. In the light of the above statements, choose the most appropriate answer from the options given below:
  • A. textBoth Statement I and Statement II are incorrect
  • B. textBoth Statement I and Statement II are correct
  • C. textStatement I is incorrect but Statement II is correct
  • D. textStatement I is correct but Statement II is incorrect

Solution

### Core Logic [Ni(H_2O)_6]^2+: Water is a weak field ligand. Ni^2+ is a 3d^8 system. In an octahedral weak field, it has 2 unpaired electrons (t_2g^6 e_g^2). Due to the presence of unpaired electrons, d-d transition is possible, making the solution green in colour. [Ni(CN)_4]^2-: CN^- is a strong field ligand. The complex is square planar (dsp^2 hybridization). All 8 electrons are paired in the lower energy d-orbitals. Because there are no unpaired electrons (diamagnetic), d-d transition does not fall in the visible region, and it is colourless. ### Step 1: Evaluate Statements Statement I is correct (Green due to unpaired electrons). Statement II is correct (Colourless as it is diamagnetic). ### Pattern Recognition Strong field ligands (like CN^-) with d^8 metal ions (Ni^2+, Pd^2+, Pt^2+) generally force pairing, creating square planar, diamagnetic, and often colourless complexes unless charge transfer occurs. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 12 Chemistry: Coordination Compounds
Q71 jee_main_2024_01_february_morning Definitions of Some Important Terms Pertaining to Coordination Compounds
Which of the following complex is homoleptic?
  • A. [Ni(CN)_4]^2-
  • B. [Ni(NH_3)_2Cl_2]
  • C. [Fe(NH_3)_4Cl_2]^+
  • D. [Co(NH_3)_4Cl_2]^+

Solution

### Core Logic A homoleptic complex is one in which the central metal atom/ion is bound to only one kind of donor group (ligand). A heteroleptic complex is one in which the central metal atom/ion is bound to more than one kind of donor group. ### Step 1: Analyze Options (1) [Ni(CN)_4]^2-: Only one type of ligand (CN^-). Homoleptic. (2) [Ni(NH_3)_2Cl_2]: Two types of ligands (NH_3 and Cl^-). Heteroleptic. (3) [Fe(NH_3)_4Cl_2]^+: Two types of ligands. Heteroleptic. (4) [Co(NH_3)_4Cl_2]^+: Two types of ligands. Heteroleptic. ### Pattern Recognition Homo = same, leptic = ligands. Look for the formula bracket containing only one symbol type after the central metal. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 12 Chemistry: Coordination Compounds
Q66 jee_main_2024_29_january_evening IUPAC Nomenclature of Coordination Complexes
The correct IUPAC name of mathrmK_2mathrmMnO_4 is
  • A. Potassium tetraoxopermanganate (VI)
  • B. Potassium tetraoxidomanganate (VI)
  • C. Dipotassium tetraoxidomanganate (VII)
  • D. Potassium tetraoxidomanganese (VI)

Solution

### Related Formula textOxidation State of Mn Evaluation: 2(+1) + x + 4(-2) = 0 ### Core Logic Solving for x: 2 + x - 8 = 0 implies x = +6 Since the complex is anionic, the metal name ends with the suffix '-ate', making it 'manganate(VI)'. The ligands are oxygen atoms, designated systematically as 'tetraoxido' or 'tetraoxo' according to newer recommendations. ### Step 1: Assembly Combining parts systematically yields the correct IUPAC string: Potassium tetraoxidomanganate(VI). ### Pattern Recognition Anionic metal centers must include the trailing '-ate' modifier followed immediately by their absolute Roman oxidation state indicators. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 12 Chemistry: Coordination Compounds
Q82 jee_main_2024_29_january_evening Brown Ring Complex Oxidation State
The oxidation number of iron in the compound formed during brown ring test for mathrmNO_3^- ion is ________.
Numerical Answer. Answer: 1 to 1

Solution

### Related Formula textFormula of Brown Ring Complex: [mathrmFe(mathrmH_2mathrmO)_5(mathrmNO)]^2+ ### Core Logic In this specific coordination complex, charge transfer occurs where nitric oxide transfers an electron to the iron center. As a result, textNO exists as a positive textNO^+ ligand, and iron drops to an unusual oxidation state: x + 5(0) + 1(+1) = +2 x + 1 = 2 implies x = +1 ### Step 1: Final Value Assignment Solving this charge balance confirms that the oxidation number of iron in the brown ring complex is +1. ### Pattern Recognition The brown ring test features a rare +1 oxidation state for iron because textNO coordinates as the positive nitrosonium cation (textNO^+). ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 12 Chemistry: Coordination Compounds
Q68 jee_main_2024_27_jan_morning Magnetic Properties of Coordination Complexes
Consider the following complex ions: P=[FeF_6]^3- Q=[V(H_2O)_6]^2+ R=[Fe(H_2O)_6]^2+ The correct order of the complex ions, according to their spin only magnetic moment values (in B.M.) is :
  • A. R < Q < P
  • B. R < P < Q
  • C. Q < R < P
  • D. Q < P < R

Solution

### Step 1: Evaluation of P=[FeF_6]^3- textFe^3+ rightarrow 3textd^5 Since textF^- is a weak field ligand, no pairing occurs. Number of unpaired electrons (n) = 5. mu = sqrt5(5+2) = sqrt35text BM ### Step 2: Evaluation of Q=[V(H_2O)_6]^2+ textV^2+ rightarrow 3textd^3 Number of unpaired electrons (n) = 3. mu = sqrt3(3+2) = sqrt15text BM ### Step 3: Evaluation of R=[Fe(H_2O)_6]^2+ textFe^2+ rightarrow 3textd^6 Since textH_2textO is a weak field ligand, configuration is textt_2textg^4 texte_textg^2. Number of unpaired electrons (n) = 4. mu = sqrt4(4+2) = sqrt24text BM ### Step 4: Comparison Comparing values: mu(Q) < mu(R) < mu(P) implies Q < R < P ### Pattern Recognition Count unpaired electrons strictly accounting for weak field vs strong field rules. Order scales monotonically with n. ### Chapter Mix Class 12 Chemistry: Coordination Compounds

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