University:
The University Of Western Ontario
Course:
CHEM 1301A | Discovering Chemical Structure
Academic year:

2024
Views:

161

Pages:

2
Author:

Kyuwon J.

Coordination Complexe Key Concepts • Coordination Complex: A structure consisting of a central metal ion bonded to surrounding ligands through coordinate covalent bonds. Example: [Ag(N H3 )2 ]+ , where Ag + is the metal ion and N H3 molecules are the ligands. • Coordination Number (CN): The total number of ligand donor atoms bonded directly to the central metal ion. – Monodentate Ligand: Contributes 1 to the CN (e.g., N H3 , H2 O). – Bidentate Ligand: Contributes 2 to the CN (e.g., en, C2 O42− ). – Polydentate Ligand: Contributes as many as the number of donor atoms. Examples with Coordination Numbers (CN) 1. Ag + and 2 I − : • Formula: [AgI2 ]− • Explanation: I − is monodentate, so 2 ligands bond to Ag + . • Coordination Number: 2 2. Ag + and 2 N H3 : • Formula: [Ag(N H3 )2 ]+ • Explanation: N H3 is monodentate, so 2 ligands bond to Ag + . • Coordination Number: 2 3. Co3+ and 6 N O2− : • Formula: [Co(N O2 )6 ]3− • Explanation: N O2− is monodentate, so 6 ligands bond to Co3+ . • Coordination Number: 6 4. N i2+ and 4 CN − : • Formula: [N i(CN )4 ]2− • Explanation: CN − is monodentate, so 4 ligands bond to N i2+ . • Coordination Number: 4 5. F e3+ and 6 SCN − : • Formula: [F e(SCN )6 ]3− • Explanation: SCN − is monodentate, so 6 ligands bond to F e3+ . • Coordination Number: 6 1 Key Terms • Ligand: A molecule or ion that donates a lone pair of electrons to the metal center. Can be neutral (e.g., H2 O) or charged (e.g., Cl− ). • Monodentate Ligand: A ligand with one donor atom (e.g., N H3 , Cl− , CN − ). • Bidentate Ligand: A ligand with two donor atoms that can bind to the metal ion (e.g., ethylenediamine (en), oxalate (C2 O42− )). • Polydentate Ligand: A ligand with several donor atoms (e.g., EDTA, which is hexadentate). • Coordination Number: The number of bonds formed between the metal ion and ligand donor atoms. Common Coordination Geometries • CN = 2: Linear (e.g., [Ag(N H3 )2 ]+ ). • CN = 4: Tetrahedral or Square Planar (e.g., [N i(CN )4 ]2− ). • CN = 6: Octahedral (e.g., [Co(N O2 )6 ]3− ). Practice Question • Determine the coordination number of the following: – Cr3+ and 6 H2 O: 6 – Cu2+ and 4 N H3 : 4 – F e2+ and 2 C2 O42− : 4 2

Coordination Complexes Notes

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