---
title: "IUPAC names of four complexes"
subject: "Engineering Chemistry"
chapter: 6
key: "semester_2/engineering_chemistry:iupac-names-2067m"
source: https://www.bctengineer.com/q/semester_2/engineering_chemistry/iupac-names-2067m
site: BCT Engineering
---

# IUPAC names of four complexes

Engineering Chemistry · Chapter 6: Coordination Complexes

- Asked in: 2067 Mangsir, 2 marks
- Video: [Naming Coordination Compounds - Chemistry](https://www.youtube.com/watch?v=yeNtqjE0dJw) — The Organic Chemistry Tutor
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_2/engineering_chemistry/iupac-names-2067m
- Whole chapter: https://www.bctengineer.com/md/semester_2/engineering_chemistry/chapter-6

## Question

Write the IUPAC name of the followings:
i) K₃[Fe(CN)₆]
ii) Na₃[Al(C₂O₄)₃]
iii) [Co Cl.CN.NO₂.(NH₃)₃]
iv) [Cr(NO₃)₆]³⁻

## Short answer

i) Potassium hexacyanoferrate(III); ii) Sodium trioxalatoaluminate(III); iii) Triamminechlorocyanonitrito-N-cobalt(III); iv) Hexanitratochromate(III) ion.

## Answer

i) K₃[Fe(CN)₆]: **potassium hexacyanoferrate(III)**
ii) Na₃[Al(C₂O₄)₃]: **sodium trioxalatoaluminate(III)**
iii) [CoCl(CN)(NO₂)(NH₃)₃]: **triamminechlorocyanonitrito-N-cobalt(III)** (the complex is neutral: Co³⁺ with Cl⁻, CN⁻, NO₂⁻)
iv) [Cr(NO₃)₆]³⁻: **hexanitratochromate(III) ion**

Ligands are in alphabetical order (ammine, chloro, cyano, nitrito).

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. What is the name of K3[Fe(CN)6]?
   A. Potassium hexacyanoferrate(II)
   B. Potassium hexacyanoiron(III)
   C. Potassium hexacyanoferrate(III)
   D. Tripotassium cyanoferrate
   Answer: C. 3 K+ means complex is 3-, so Fe is +3. (Key point: Name of K3[Fe(CN)6])

2. What is the name of Na3[Al(C2O4)3]?
   A. Sodium trioxalatoaluminate(III)
   B. Sodium aluminiumoxalate(III)
   C. Trisodium oxalatoaluminium
   D. Sodium trioxalatoaluminium(III)
   Answer: A. Anionic complex gets -ate; Al is +3. (Key point: Name of Na3[Al(C2O4)3])

3. In what order are the ligands named in [CoCl(CN)(NO2)(NH3)3]?
   A. chloro, cyano, nitrito, ammine
   B. nitrito, cyano, chloro, ammine
   C. by charge order
   D. ammine, chloro, cyano, nitrito
   Answer: D. Ligands are listed alphabetically ignoring numerical prefixes. (Key point: Alphabetical order)

4. What is the name of [Cr(NO3)6]3-?
   A. Hexanitratochromium(III) ion
   B. Hexanitratochromate(III) ion
   C. Hexanitritochromate(III) ion
   D. Hexanitratochromate(VI) ion
   Answer: B. Anionic complex uses chromate; Cr is +3 since x - 6 = -3. (Key point: Name of [Cr(NO3)6]3-)

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