Isomerism in coordination compounds.pptx

Examples of Coordination Compounds

  • [(NH3)5Cr Cr(NH3)5] Cl5: µ-hydroxo-bis-pentaamine Chromium(III)

  • [(NH3)4Co Co(NH3)4]4+: µ-amido µ-hydroxo octaminedicobalt(III)

  • [Zn(OH)4]2-: Tetra hydroxo Zincate(II)

  • [Co(NO2)3(NH3)3]: Triammine trinitrocobalt(III)

  • [Co(NH3)6][Cr(C2O4)3]: Hexamminecobalt(III) trioxalatochromate(III)

  • NH4[Cr(SCN)4(NH3)2]: Ammonium diamine tetrathiocyanato chromate(III)

Isomerism in Coordination Compounds

  • Isomerism Defined: Compounds with the same formula but different structures (isomers).

  • Types of Isomerism:

    • Stereoisomerism

    • Structural Isomerism:

      • Geometrical

      • Optical

      • Linkage

      • Ionization

      • Coordination

      • Solvate (Hydrate)

Coordination Isomerism: Isomerism from ligand interchange between cation and anion. Example: [Co(NH3)6][Cr(CN)6] vs [Cr(NH3)6][Co(CN)6].

Linkage Isomerism: Ligands with multiple donor atoms can create scenarios like in NO2-.

Ionization Isomerism: Group exchange between the complex and external ions. Example: [Co(NH3)5Br]SO4 vs [Co(NH3)5SO4]Br.

Hydrate Isomerism: Varying amounts of H2O inside vs. outside the coordination sphere. Example: [Cr(H2O)6]Cl3 and its variants.

Geometrical Isomerism: Arrangements can be cis or trans. Example: cis- and trans- Pt(NH3)2Cl2.

Optical Isomers: Non-superimposable mirror images (enantiomers) that are chiral. Significant in pharmaceuticals due to differing effects.

  • Optical Activity: Dextrorotatory (d-isomer) rotates light right; Levorotatory (l-isomer) left. Racemic mixtures show no optical activity due to equal parts of both isomers.