---
title: "IUPAC names of four complexes"
subject: "Engineering Chemistry"
chapter: 6
key: "semester_2/engineering_chemistry:iupac-names-2072m"
source: https://www.bctengineer.com/q/semester_2/engineering_chemistry/iupac-names-2072m
site: BCT Engineering
---

# IUPAC names of four complexes

Engineering Chemistry · Chapter 6: Coordination Complexes

- Asked in: 2072 Magh, 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-2072m
- Whole chapter: https://www.bctengineer.com/md/semester_2/engineering_chemistry/chapter-6

## Question

Write IUPAC name of the following co-ordination compounds.
i) Na₃[Al(C₂O₄)₃]
ii) [Co(NH₃)₆]Cl₃
iii) [Pb(OH)₄]²⁻
iv) [Cr(H₂O)₅Cl]Cl₂

## Short answer

i) sodium trioxalatoaluminate(III), ii) hexaamminecobalt(III) chloride, iii) tetrahydroxoplumbate(II) ion, iv) pentaaquachlorochromium(III) chloride.

## Answer

i) Na₃[Al(C₂O₄)₃]: **sodium trioxalatoaluminate(III)**
ii) [Co(NH₃)₆]Cl₃: **hexaamminecobalt(III) chloride**
iii) [Pb(OH)₄]²⁻: **tetrahydroxoplumbate(II) ion** (charge: x + 4(−1) = −2, so x = +2)
iv) [Cr(H₂O)₅Cl]Cl₂: **pentaaquachlorochromium(III) chloride**

The Latin stem "plumb-" is used for lead in anionic complexes.

## Check yourself

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

1. What is the IUPAC name of [Co(NH3)6]Cl3?
   A. hexaamminecobalt(III) chloride
   B. hexaaminecobalt(II) chloride
   C. cobalt hexaammine chloride
   D. hexaamminecobaltate(III) chloride
   Answer: A. The correct option is: hexaamminecobalt(III) chloride. This follows from the answer on name. (Key point: Name)

2. What stem and oxidation state apply to Pb in [Pb(OH)4]2-?
   A. leadate, +2
   B. plumbate, +2
   C. plumbate, +4
   D. plumbate, +6
   Answer: B. The correct option is: plumbate, +2. This follows from the answer on pb. (Key point: Pb)

3. What is the ligand name for OH- in IUPAC names?
   A. hydroxy
   B. hydroxide
   C. hydroxo
   D. oxo
   Answer: C. The correct option is: hydroxo. This follows from the answer on hydroxo. (Key point: Hydroxo)

## Close variants set in other exams

- [IUPAC names of four complexes](https://www.bctengineer.com/question.md?key=semester_2%2Fengineering_chemistry%3Aiupac-names-2070) — Engineering Chemistry, chapter 6, asked 4×
- [IUPAC names of four complexes](https://www.bctengineer.com/question.md?key=semester_2%2Fengineering_chemistry%3Aiupac-names-2070m) — Engineering Chemistry, chapter 6, asked 4×
- [IUPAC names of two complexes](https://www.bctengineer.com/question.md?key=semester_2%2Fengineering_chemistry%3Aiupac-names-2069) — Engineering Chemistry, chapter 6, asked 4×

## Related in Engineering Chemistry

- [IUPAC names of four complexes](https://www.bctengineer.com/question.md?key=semester_2%2Fengineering_chemistry%3Aiupac-names-2067m) — Engineering Chemistry, chapter 6
- [IUPAC names of four complexes](https://www.bctengineer.com/question.md?key=semester_2%2Fengineering_chemistry%3Aiupac-names-2069p) — Engineering Chemistry, chapter 6
- [IUPAC names of four complexes](https://www.bctengineer.com/question.md?key=semester_2%2Fengineering_chemistry%3Aiupac-names-2072) — Engineering Chemistry, chapter 6
- [IUPAC names and EAN of complexes](https://www.bctengineer.com/question.md?key=semester_2%2Fengineering_chemistry%3Aiupac-ean) — Engineering Chemistry, chapter 6
- [Chelate, Sidgwick theory, IUPAC names](https://www.bctengineer.com/question.md?key=semester_2%2Fengineering_chemistry%3Achelate-sidgwick) — Engineering Chemistry, chapter 6
- [Principal and auxiliary valencies; IUPAC names](https://www.bctengineer.com/question.md?key=semester_2%2Fengineering_chemistry%3Aprimary-secondary-valency) — Engineering Chemistry, chapter 6

## Related in other subjects

- [Define co-ordination in protection](https://www.bctengineer.com/question.md?key=semester_6%2Fswitchgear_and_protection%3Adefine-coordination) — Switchgear and Protection, chapter 1