# C.I. Pigment Yellow 42

**CAS:** 51274-00-1  
**PubChem CID:** [23320441](https://pubchem.ncbi.nlm.nih.gov/compound/23320441)  
**Molecular formula:** FeH₃O₃  
**Molar mass:** 106.87 g/mol  
**IUPAC:** iron(3+);oxygen(2-);hydroxide;hydrate  
**SMILES:** `O.[OH-].[O-2].[Fe+3]`  
**InChIKey:** `LDHBWEYLDHLIBQ-UHFFFAOYSA-M`  
**InChI:** `InChI=1S/Fe.2H2O.O/h;2*1H2;/q+3;;;-2/p-1`  

## Physicochemical properties

| Parameter | Value |
|---|---|
| PSA | 3 Ų |
| Hydrogen bond donors | 2 |
| Hydrogen bond acceptors | 3 |
| Rotatable bonds | 0 |
| Heavy atoms | 4 |

## 3D structure

The molecule contains 7 atoms connected by 3 chemical bonds. Interactive 3D model available at: https://molgod.org/molecule/51274-00-1/

## Synonyms

- Ferric oxide Yellow
- EX438O2MRT
- C.I. 77492
- RefChem:1080569
- 51274-00-1
- Yellow iron oxide
- Iron Oxide Yellow
- Ferric oxide, yellow
- Bayferrox 920
- UNII-EX438O2MRT

## Data sources

- [PubChem CID 23320441](https://pubchem.ncbi.nlm.nih.gov/compound/23320441)
- [NIST WebBook](https://webbook.nist.gov/cgi/cbook.cgi?ID=51274-00-1)
- [ChEMBL](https://www.ebi.ac.uk/chembl/g/#search_results/all/query=51274-00-1)

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**How to cite:** MolGod.org. "C.I. Pigment Yellow 42 (CAS 51274-00-1)." Last modified 2026-10-03. https://molgod.org/molecule/51274-00-1/ — for a chemical fact, cite its primary source (PubChem CID 23320441); for a 3D model file, cite its MolGod ID, the variant and the SHA-256 from its licence record.

*Last updated: 2026-10-03 · Generator: MOL-GOD v3.12.33*