ChemistryMediumClass 12

IUPAC Nomenclature — Naming complex compounds

Coordination Compounds

JEE Qs

Hard

min

Master the systematic application of IUPAC rules for naming coordination compounds by consistent practice, focusing on oxidation state calculation and correct ligand ordering and naming.

🧮 Key Formulas

General Rule: Cation Name followed by Anion Name.

Complex Part: Ligands named alphabetically (ignoring numerical prefixes) before the central metal.

Numerical Prefixes: di-, tri-, tetra- for simple ligands; bis-, tris-, tetrakis- for complex ligands or ligands with names already containing di, tri, etc.

Anionic Ligands: Suffix -o (e.g., chloro, hydroxo, cyano).

Neutral Ligands: Common names (e.g., ammine for NH3, aqua for H2O, carbonyl for CO, nitrosyl for NO).

Central Metal Oxidation State: Indicated by Roman numeral in parentheses immediately after the metal name.

Complex Anion Suffix: If the complex is an anion, the metal name ends with -ate (e.g., ferrate, cuprate, argentate).

Counter-ions: Named without numerical prefixes.

✅ Key Points for JEE

1Always determine the oxidation state of the central metal ion accurately, as it's crucial for correct nomenclature and a common source of error.
2Ligands are listed in alphabetical order *ignoring* the numerical prefixes (di, tri, bis, tris). For example, 'diammine' comes before 'chloro', not 'dichloro'.
3Remember the special names for common neutral ligands like aqua (H2O), ammine (NH3), carbonyl (CO), and nitrosyl (NO).
4Pay close attention to whether the complex ion is cationic, anionic, or neutral, as this dictates whether the central metal's name will end in '-ate' or remain unchanged.
5Practice naming from both structure to name and name to structure to solidify understanding and identify potential ambiguities.

⚠️ Common Mistakes

✕Incorrectly calculating the oxidation state of the central metal ion.
✕Failure to apply the '-ate' suffix when the complex ion is anionic.
✕Incorrect alphabetical ordering of ligands by including numerical prefixes (e.g., 'dichloro' before 'ethylenediamine').
✕Misuse of simple (di, tri) vs. complex (bis, tris) numerical prefixes for ligands.
✕Forgetting to enclose the oxidation state of the metal in Roman numerals within parentheses.

📝 Practice Questions

See all

Q74.In the Claisen-Schmidt reaction to prepare, dibenzalacetone from 5.3 g of benzaldehyde, a total of 3.51 g of product was obtained. The percentage yield in this reaction was ______ %.

2025·NumericalHard

Q61.The calculated spin-only magnetic moments of K3 [Fe(OH)6] and K4 [Fe(OH)6] respectively are : (1) 3.87 and 4.90 B.M. (2) 4.90 and 5.92 B.M. (3) 4.90 and 4.90 B.M. (4) 5.92 and 4.90 B.M.

2025·MCQMedium

Q54.Identify the homoleptic complexes with odd number of d electrons in the central metal : (A) [FeO4]2− (B) [Fe(CN)6]3− (C) [Fe(CN)5NO]2− (D) [CoCl4]2− (E) [Co(H2O)3 F3] Choose the correct answer from the options given below : (1) (A), (B) and (D) only (2) (C) and (E) only (3) (B) and (D) only (4) (A), (C) and (E) only

2025·MCQMedium

Q68.In which of the following complexes the CFSE, Δo will be equal to zero? (1) [Fe(en)3]Cl3 (2) K4 [Fe(CN)6] (3) [Fe(NH3)6]Br2 (4) K3 [Fe(SCN)6]

2025·MCQMedium

Q70.From the magnetic behaviour of [NiCl4]2− (paramagnetic) and [Ni(CO)4] (diamagnetic), choose the correct geometry and oxidation state. (1) [NiCl4]2−: NiII , tetrahedral [Ni(CO)4] : NiII , (2) [NiCl4]2− : NiII , square planar [Ni(CO)4] : Ni(0) square planar , square planar (3) [NiCl4]2−: NiII , tetrahedral [Ni(CO)4] : Ni(0), (4) [NiCl4]2−: Ni(0), tetrahedral [Ni(CO)4] : Ni(0), tetrahedral square planar

2025·MCQHard

Q53.The correct order of the following complexes in terms of their crystal field stabilization energies is : (1) [Co(NH3)4]2+ < [Co(NH3)6]2+ < [Co(en)3]3+ < [Co(NH3)6]3+ (2) [Co(NH3)6]2+ < [Co(NH3)6]3+ < [Co(NH3)4]2+ < [Co(en)3]3+ (3) [Co(en)3]3+ < [Co(NH3)6]3+ < [Co(NH3)6]2+ < [Co(NH3)4]2+ (4) [Co(NH3)4]2+ < [Co(NH3)6]2+ < [Co(NH3)6]3+ < [Co(en)3]3+

2025·MCQHard

NCERT Chapters

Class 12 Chemistry Ch 9: Coordination Compounds