A coordination compound contains a central metal atom or ion bonded to a fixed number of ions or neutral molecules called ligands, the whole assembly (the coordination sphere) written inside square brackets, with any ions balancing charge outside it. This is fundamentally different from a double salt: a double salt such as carnallite, , or Mohr's salt, $\
Coordination Compounds
Class 1214 previous-year questions from this chapter every option and the correct answer, free · where the marks are
1. Nomenclature and Werner's theory
Exam focus: Werner's key distinction is primary valence (ionisable, the oxidation state) versus secondary valence (non-ionisable, the fixed coordination number and geometry) — a complex's conductivity in solution tests exactly this, since only ions outside the coordination sphere carry current. In naming, ligands are listed alphabetically by name regardless of charge or multiplying prefix (bis, tris), and an anionic complex ion always ends in "-ate."
Werner's Theory of Coordination Compounds
Competition Wallah
Covers the introduction and Werner's theory in depth; IUPAC nomenclature is taught in the next lecture of the same series, not fully in this one.
ChemistryNEET 2024show ▾Given below are two statements:
Statement I: is a homoleptic complex whereas is a heteroleptic complex.
Statement II: The complex has only one kind of ligand but has more than one kind of ligand.
In the light of the above statements, choose the correct answer from the options given below:
- A.Both Statement I and Statement II are false
- B.Statement I is true but Statement II is false
- C.Statement I is false but Statement II is true
- D.Both Statement I and Statement II are true✓
Solution
A homoleptic complex has only one kind of ligand (); a heteroleptic one has more than one kind (). Both statements are true and II is the definition behind I.
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Save for spaced revision (free account)ChemistryNEET 2023show ▾The homoleptic complex from the following complexes is:
- A.Potassium trioxalatoaluminate(III)✓
- B.Diamminechloridonitrito-N-platinum(II)
- C.Pentaamminecarbonatocobalt(III) chloride
- D.Triamminetriaquachromium(III) chloride
The worked solution is part of a paid pack.
ChemistryNEET 2022show ▾The IUPAC name of the complex is:
- A.diaquasilver(I) dicyanidoargentate(I)✓
- B.dicyanidosilver(II) diaquaargentate(II)
- C.diaquasilver(II) dicyanidoargentate(II)
- D.dicyanidosilver(I) diaquaargentate(I)
The worked solution is part of a paid pack.
ChemistryNEET 2021show ▾The ethylenediaminetetraacetate (EDTA) ion is:
- A.A hexadentate ligand with four O and two N donor atoms✓
- B.A unidentate ligand
- C.A bidentate ligand with two N donor atoms
- D.A tridentate ligand with three N donor atoms
The worked solution is part of a paid pack.
2. Isomerism in coordination compounds
Exam focus: Ambidentate ligands like NO₂⁻/ONO⁻ (nitro/nitrito) and SCN⁻/NCS⁻ give linkage isomers — same formula, different donor atom — a distinct category from ionisation isomerism, where a different ion sits inside versus outside the coordination sphere. For an MA₃B₃ octahedral complex, the geometrical isomers are called fac and mer, not cis/trans, which is reserved for the MA₄B₂ and MA₂B₂ patterns.
Isomerism in Coordination Compounds (Part 1)
Competition Wallah
Covers structural isomerism in coordination compounds; explicitly "Part 1" — stereoisomerism (geometrical/optical) is covered in a follow-up Part 2 video not included here.
ChemistryNEET 2024show ▾Match List I with List II.
List I (Complex) List II (Type of isomerism) A. I. Solvate isomerism B. II. Linkage isomerism C. III. Ionisation isomerism D. IV. Coordination isomerism
Choose the correct answer from the options given below:
- A.A-I, B-III, C-IV, D-II
- B.A-I, B-IV, C-III, D-II
- C.A-II, B-IV, C-III, D-I
- D.A-II, B-III, C-IV, D-I✓
Solution
can bind through N or O — linkage isomerism (A-II). Exchanging and between coordination sphere and counter-ion — ionisation isomerism (B-III). Two complex ions can swap ligands — coordination isomerism (C-IV). Water inside versus outside the sphere — solvate/hydrate isomerism (D-I).
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Save for spaced revision (free account)3. Valence bond and crystal field theory
Exam focus: Tetrahedral crystal-field splitting is always smaller than octahedral for the same metal and ligands (roughly 4/9 the size) — small enough that tetrahedral complexes are almost always high-spin regardless of the ligand, unlike octahedral complexes where a strong-field ligand like CN⁻ or CO forces low-spin pairing. VBT explains a complex's geometry and magnetic moment through hybridisation, but not why it's coloured or why one ligand counts as "strong field" — that gap is exactly what crystal field theory fills.
Coordination Compounds: Crystal Field Theory
NCERT Wallah
d-orbital splitting, strong- vs weak-field ligands, high-spin vs low-spin — the half of this subtopic NEET weights more heavily. Valence bond theory is lecture 03 in the same series.
ChemistryNEET 2025show ▾The correct order of the wavelength of light absorbed by the following complexes is:
A. · B. · C. · D.
Choose the correct answer from the options given below:
- A.B < D < A < C
- B.B < A < D < C✓
- C.C < D < A < B
- D.C < A < D < B
Solution
Wavelength absorbed is inversely related to . (strongest field) gives the largest splitting, then ; with water splits less, and with water least (absorbs in the red, ~800 nm). So B < A < D < C.
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Save for spaced revision (free account)ChemistryNEET 2025show ▾Which of the following are paramagnetic?
A. · B. · C. · D. · E.
Choose the correct answer from the options given below:
- A.A and C only
- B.B and E only
- C.A and D only✓
- D.A, D and E only
Solution
(, , weak-field tetrahedral) has two unpaired electrons; so does (octahedral ). and contain Ni(0), ; is square planar , all paired. Paramagnetic: A and D.
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Save for spaced revision (free account)ChemistryNEET 2024show ▾Given below are two statements:
Statement I: Both and complexes are octahedral but differ in their magnetic behaviour.
Statement II: is diamagnetic whereas is paramagnetic.
In the light of the above statements, choose the correct answer from the options given below:
- A.Both Statement I and Statement II are false
- B.Statement I is true but Statement II is false
- C.Statement I is false but Statement II is true
- D.Both Statement I and Statement II are true✓
Solution
Both are octahedral () complexes. is a strong-field ligand, giving low-spin — diamagnetic. is weak-field, giving high-spin with four unpaired electrons — paramagnetic. Both statements are true.
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Save for spaced revision (free account)ChemistryNEET 2023show ▾Which complex compound is the most stable?
ChemistryNEET 2022show ▾The order of energy absorbed, which is responsible for the colour of the complexes
(A)
(B) and
(C)
is:
- A.(B) > (A) > (C)
- B.(A) > (B) > (C)
- C.(C) > (B) > (A)
- D.(C) > (A) > (B)✓
The worked solution is part of a paid pack.
ChemistryNEET 2021show ▾Match List-I with List-II.
List-I List-II (a) (i) 5.92 BM (b) (ii) 0 BM (c) (iii) 4.90 BM (d) (iv) 1.73 BM
Choose the correct answer from the options given below:
- A.(a)-(iv), (b)-(ii), (c)-(i), (d)-(iii)
- B.(a)-(ii), (b)-(iv), (c)-(iii), (d)-(i)
- C.(a)-(i), (b)-(iii), (c)-(iv), (d)-(ii)
- D.(a)-(iv), (b)-(i), (c)-(ii), (d)-(iii)✓
The worked solution is part of a paid pack.
ChemistryNEET 2020show ▾Which of the following is the correct order of increasing field strength of ligands in forming coordination compounds?
ChemistryNEET 2020show ▾The calculated spin-only magnetic moment of the ion is:
- A.3.87 BM
- B.4.90 BM✓
- C.5.92 BM
- D.2.84 BM
The worked solution is part of a paid pack.