Electron accountancy
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Subject classification: this is a chemistry resource. |
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Type classification: this is a lesson resource. |
Aims
[edit | edit source]This Lesson will cover:
- Revision of electron counting methods
- The Covalent Bond Classification as an alternative method
- Simple classes of ligand and bond ambiguities
- Curly arrow conventions in complexes
- Composite ligands
- Formal oxidation state and the d-electron count
- Coordination number and ambiguities
Classes of ligand
[edit | edit source]L ligands (2e donors)
[edit | edit source]- PR3, N2, C2H4, CO, H2, C2H2
- observed as neutral
X ligands (1e donors)
[edit | edit source]- H, halides, R (alkyl), Ar (aryl), COR (acyl), OR (alkoxides), NR2
- observed as anions
Composite ligands
[edit | edit source]Electron counting
[edit | edit source]The number of electrons donated by the metal = its group number.
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Valence Number (VN)
VN = number of X ligands + charge on complex |
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Coordination Number (CN)
CN = number of atoms bonded to the metal CN = number of electron pairs added to the metal CN = number of ligands bonded to the metal |
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Ligand Bond Number (LBN)
LBN = sum of L and X ligands |