Coordinate Compounds

  • Definition: Compounds in which a central metal ion is surrounded by ligands.
  • Ligands: Molecules or ions that donate electron pairs to the metal ion.
  • Examples: VO(ac)2

Coordination Number

  • Definition: The number of ligands directly attached to the central metal ion.
  • Examples:
    • VO(ac)2 has a coordination number of 2.
    • [Fe(CN)6]3-(Fe(CN)63-) has a coordination number of 6.

Ligands

  • Definition: Molecules or ions that donate electron pairs to the metal ion.
  • Types of Ligands:
    • Monodentate: Ligands that donate only one electron pair.
    • Polydentate: Ligands that donate multiple electron pairs.
  • Examples:
    • Monodentate Ligands: H2O, NH3
    • Polydentate Ligands: EDTA, ethylenediamine

Nomenclature of Coordinate Compounds

  • Example: [Co(NH3)6]Cl3
  • Prefix: “Hexa” for the coordination number 6.
  • Central Metal Ion: Cobalt (Co)
  • Ligands: Ammonia (NH3)
  • Charge of Complex: 3+
  • Anion: Chloride (Cl-)

Isomerism in Coordinate Compounds

  • Definition: Different arrangements of atoms or groups in a compound.
  • Types of Isomerism:
    • Structural Isomerism: Different connectivity of atoms.
    • Stereoisomerism: Same connectivity of atoms, but different spatial arrangement.
  • Example:
    • [Co(NH3)6]Cl3 exists as both cis and trans isomers.

Bonding in Coordinate Compounds

  • Types of Bonds:
    • Coordinate Covalent Bond: Bond formed between the metal ion and the ligand.
      • Example: N coordinate to Co in [Co(NH3)6]Cl3.
    • Metal-Ligand Bond: Bond formed between the metal ion and the ligand.
      • Example: Co-N bond in [Co(NH3)6]Cl3.

Crystal Field Theory

  • Definition: A model used to explain the bonding and properties of coordination compounds.
  • Crystal Field Splitting: Separation of energy levels of the metal ion due to the presence of ligands.
  • Types of Crystal Field Theory:
    • Octahedral Crystal Field Theory: For complexes with coordination number 6.
    • Tetrahedral Crystal Field Theory: For complexes with coordination number 4.

Octahedral Crystal Field Theory

  • Definition: Theory explaining the energy level splitting in octahedral coordination complexes.
  • Low Spin Complex: Fewer electrons occupy the higher energy level orbitals.
  • High Spin Complex: More electrons occupy the higher energy level orbitals.
  • Example: [Co(NH3)6]3+ is a low spin complex.

Tetrahedral Crystal Field Theory

  • Definition: Theory explaining the energy level splitting in tetrahedral coordination complexes.
  • Similar to the octahedral theory, but with different energy level splitting.
  • Example: [FeCl4]- is a tetrahedral complex.

Coordination Compounds in Biological Systems

  • Examples:
    • Hemoglobin: Iron (Fe) in heme group coordinated with oxygen (O2).
    • Chlorophyll: Magnesium (Mg) coordinated with a porphyrin molecule.
    • Vitamin B12: Cobalt (Co) coordinated with a corrin ring structure.

Coordination Compounds - VO(ac)2 compound

  • Definition: A coordination compound in which a central metal ion, vanadium (V), is coordinated with two acetylacetonate (ac) ligands.
  • Ligands: Acetylacetonate (ac)
  • Chemical Formula: VO(ac)2
  • Examples: VO(ac)2 [VO(ac)2]2+
  • Properties:
    • Contains a vanadium ion in the +5 oxidation state.
    • The acetylacetonate ligands donate two electron pairs each.
    • Has a square planar molecular geometry.

Coordination Compounds - Coordination Number and Ligands

  • Coordination Number: The number of ligands directly attached to the central metal ion.
    • In VO(ac)2, the coordination number is 2.
  • Ligands: Molecules or ions that donate electron pairs to the metal ion.
    • In VO(ac)2, the ligands are acetylacetonate (ac).

Coordination Compounds - Nomenclature

  • Nomenclature of VO(ac)2:
    • Prefix “di” for the coordination number 2.
    • Central Metal Ion: Vanadium (V)
    • Ligands: Acetylacetonate (ac)
  • Chemical Name: Dichlorobis (acetylacetonato) vanadium (V).

Coordination Compounds - Isomerism

  • Isomerism: Different arrangements of atoms or groups in a compound.
  • Types of Isomerism:
    • Structural Isomerism: Different connectivity of atoms.
    • Stereoisomerism: Same connectivity of atoms, but different spatial arrangement.
  • Examples:
    • VO(ac)2 does not exhibit isomerism as both acetylacetonate ligands are identical.

Coordination Compounds - Bonding

  • Bonding in VO(ac)2:
    • Coordinate Covalent Bonds: Bonds formed between the vanadium ion and the acetylacetonate ligands.
    • Metal-Ligand Bonds: Bonds formed between the vanadium ion and the ligands.
  • Example:
    • The bond between the vanadium ion and each acetylacetonate ligand in VO(ac)2 is a coordinate covalent bond.

Crystal Field Theory - Introduction

  • Crystal Field Theory: A model used to explain the bonding and properties of coordination compounds.
  • Crystal Field Splitting: Separation of energy levels of the metal ion due to the presence of ligands.
  • Applications of Crystal Field Theory:
    • Explains the color observed in coordination compounds.
    • Predicts the magnetic behavior of coordination compounds.

Octahedral Crystal Field Theory

  • Octahedral Crystal Field Theory: Theory explaining the energy level splitting in octahedral coordination complexes.
  • Low Spin Complex: When electrons fill the lower energy level orbitals first.
  • High Spin Complex: When electrons occupy higher energy level orbitals.
  • Example: [Co(NH3)6]3+ is a low spin complex.

Tetrahedral Crystal Field Theory

  • Tetrahedral Crystal Field Theory: Theory explaining the energy level splitting in tetrahedral coordination complexes.
  • Similar to the octahedral theory, but with different energy level splitting.
  • Example: [FeCl4]- is a tetrahedral complex.

Coordination Compounds in Biological Systems

  • Examples of coordination compounds in biological systems:
    • Hemoglobin: Iron (Fe) in heme group coordinated with oxygen (O2).
    • Chlorophyll: Magnesium (Mg) coordinated with a porphyrin molecule.
    • Vitamin B12: Cobalt (Co) coordinated with a corrin ring structure.
  • Importance of coordination compounds in biological processes.

Coordination Compounds - VO(ac)2 compound

  • Definition: A coordination compound in which a central metal ion, vanadium (V), is coordinated with two acetylacetonate (ac) ligands.
  • Ligands: Acetylacetonate (ac)
  • Chemical Formula: VO(ac)2
  • Examples: VO(ac)2 [VO(ac)2]2+
  • Properties:
    • Contains a vanadium ion in the +5 oxidation state.
    • The acetylacetonate ligands donate two electron pairs each.
    • Has a square planar molecular geometry.

Coordination Compounds - Coordination Number and Ligands

  • Coordination Number: The number of ligands directly attached to the central metal ion.
    • In VO(ac)2, the coordination number is 2.
  • Ligands: Molecules or ions that donate electron pairs to the metal ion.
    • In VO(ac)2, the ligands are acetylacetonate (ac).

Coordination Compounds - Nomenclature

  • Nomenclature of VO(ac)2:
    • Prefix “di” for the coordination number 2.
    • Central Metal Ion: Vanadium (V)
    • Ligands: Acetylacetonate (ac)
  • Chemical Name: Dichlorobis (acetylacetonato) vanadium (V).

Coordination Compounds - Isomerism

  • Isomerism: Different arrangements of atoms or groups in a compound.
  • Types of Isomerism:
    • Structural Isomerism: Different connectivity of atoms.
    • Stereoisomerism: Same connectivity of atoms, but different spatial arrangement.
  • Examples:
    • VO(ac)2 does not exhibit isomerism as both acetylacetonate ligands are identical.

Coordination Compounds - Bonding

  • Bonding in VO(ac)2:
    • Coordinate Covalent Bonds: Bonds formed between the vanadium ion and the acetylacetonate ligands.
    • Metal-Ligand Bonds: Bonds formed between the vanadium ion and the ligands.
  • Example:
    • The bond between the vanadium ion and each acetylacetonate ligand in VO(ac)2 is a coordinate covalent bond.

Crystal Field Theory - Introduction

  • Crystal Field Theory: A model used to explain the bonding and properties of coordination compounds.
  • Crystal Field Splitting: Separation of energy levels of the metal ion due to the presence of ligands.
  • Applications of Crystal Field Theory:
    • Explains the color observed in coordination compounds.
    • Predicts the magnetic behavior of coordination compounds.

Octahedral Crystal Field Theory

  • Octahedral Crystal Field Theory: Theory explaining the energy level splitting in octahedral coordination complexes.
  • Low Spin Complex: When electrons fill the lower energy level orbitals first.
  • High Spin Complex: When electrons occupy higher energy level orbitals.
  • Example: [Co(NH3)6]3+ is a low spin complex.

Tetrahedral Crystal Field Theory

  • Tetrahedral Crystal Field Theory: Theory explaining the energy level splitting in tetrahedral coordination complexes.
  • Similar to the octahedral theory, but with different energy level splitting.
  • Example: [FeCl4]- is a tetrahedral complex.

Coordination Compounds in Biological Systems

  • Examples of coordination compounds in biological systems:
    • Hemoglobin: Iron (Fe) in heme group coordinated with oxygen (O2).
    • Chlorophyll: Magnesium (Mg) coordinated with a porphyrin molecule.
    • Vitamin B12: Cobalt (Co) coordinated with a corrin ring structure.
  • Importance of coordination compounds in biological processes.