Inorganic · Organometallics
Organometallic Chemistry: 18-Electron Rule & Key Reactions
Exam-focused revision notes on Organometallic Chemistry: 18-Electron Rule & Key Reactions for CSIR-NET Chemical Sciences, GATE Chemistry and IIT-JAM — the core concepts, the formulas worth memorising, the traps that cost marks, and a quick-recall table.
The 18-electron rule
Stable organometallic complexes tend to have 18 valence electrons around the metal — a filled (n−1)d, ns, np shell. Two equivalent counting methods exist and both give the same total; just be consistent within one calculation.
What this note covers
- 1The 18-electron rule
- 2Electron donation by common ligands
- 3Hapticity (η notation)
- 4Metal carbonyls
- 5Key elementary steps
- 6Named catalytic cycles (brief)
- 7Common traps students miss
- 830-second recall table
Read the full note
The remaining 7 sections — including the worked examples, the common-traps list and the quick-recall table — are part of ChemVidya Full Access, along with 6,000+ practice questions.
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