Slide 1 - Introduction to Coordinate Compounds

  • Coordinate compounds are formed by the coordination of a central metal ion or atom with one or more ligands.
  • Ligands are molecules or ions that donate a pair of electrons to form a coordinate bond with the metal.
  • The coordination number indicates the number of bonds formed between the metal ion and the ligands.

Slide 2 - Monodentate Ligands

  • Monodentate ligands have only one donor atom capable of forming a single coordinate bond with the metal ion.
  • Examples of monodentate ligands include ammonia (NH3), water (H2O), chloride ion (Cl-), etc.
  • The coordination number of the metal ion in monodentate complexes is equal to the number of monodentate ligands bonded to it.

Slide 3 - Bidentate Ligands

  • Bidentate ligands have two donor atoms capable of forming two coordinate bonds with the metal ion.
  • Ethylenediamine (en) and oxalate ion (C2O4^2-) are examples of bidentate ligands.
  • The coordination number of the metal ion in bidentate complexes is twice the number of bidentate ligands bonded to it.

Slide 4 - Polydentate Ligands

  • Polydentate ligands have multiple donor atoms capable of forming multiple coordinate bonds with the metal ion.
  • Ethylenediaminetetraacetate (EDTA) and diethylenetriaminepentaacetate (DTPA) are examples of polydentate ligands.
  • The coordination number in polydentate complexes depends on the number of donor atoms in the ligands.

Slide 5 - Chelating Ligands

  • Chelating ligands are a type of polydentate ligands that form a ring structure called a chelate with the metal ion.
  • The formation of chelate rings increases the stability of the complex.
  • Ethylenediaminetetraacetate (EDTA) is a common chelating ligand.

Slide 6 - Examples of Monodentate Ligands

  • Ammonia (NH3) - forms coordinate bond with metal ions like Cu2+, Ni2+, etc.
  • Water (H2O) - forms coordinate bond with metal ions like Fe3+, Cr3+, etc.
  • Chloride ion (Cl-) - forms coordinate bond with metal ions like Ag+, Pt2+, etc.

Slide 7 - Examples of Bidentate Ligands

  • Ethylenediamine (en) - forms two coordinate bonds with metal ions like Cu2+, Fe2+, etc.
  • Oxalate ion (C2O4^2-) - forms two coordinate bonds with metal ions like Mn2+, Co2+, etc.

Slide 8 - Examples of Polydentate Ligands

  • Ethylenediaminetetraacetate (EDTA) - forms multiple coordinate bonds with metal ions like Zn2+, Ca2+, etc.
  • Diethylenetriaminepentaacetate (DTPA) - forms multiple coordinate bonds with metal ions like Cd2+, Mg2+, etc.

Slide 9 - Applications of Coordinate Compounds

  • Coordination compounds have various applications in chemistry and industry.
  • They are used as catalysts in chemical reactions.
  • Some coordination compounds are employed in medicine for their therapeutic properties.

Slide 10 - Summary

  • Coordinate compounds are formed by the coordination of a metal ion with one or more ligands.
  • Monodentate ligands have one donor atom, bidentate ligands have two, and polydentate ligands have multiple donor atoms.
  • Chelating ligands form ring structures with the metal ion.
  • Examples of ligands include ammonia, water, chloride ion, ethylenediamine, oxalate ion, EDTA, and DTPA.
  • Coordinate compounds find applications in catalysts and medicine.

Slide 11 - Examples of Monodentate Ligands

  • Ammonia (NH3)
    • Forms a coordinate bond with metal ions like Cu2+, Ni2+, etc.
    • Example: [Cu(NH3)4]2+
  • Water (H2O)
    • Forms a coordinate bond with metal ions like Fe3+, Cr3+, etc.
    • Example: [Fe(H2O)6]3+
  • Chloride ion (Cl-)
    • Forms a coordinate bond with metal ions like Ag+, Pt2+, etc.
    • Example: [AgCl2]-

Slide 12 - Examples of Bidentate Ligands

  • Ethylenediamine (en)
    • Forms two coordinate bonds with metal ions like Cu2+, Fe2+, etc.
    • Example: [Cu(en)2]2+
  • Oxalate ion (C2O4^2-)
    • Forms two coordinate bonds with metal ions like Mn2+, Co2+, etc.
    • Example: [Mn(C2O4)3]4-

Slide 13 - Examples of Polydentate Ligands

  • Ethylenediaminetetraacetate (EDTA)
    • Forms multiple coordinate bonds with metal ions like Zn2+, Ca2+, etc.
    • Example: [Zn(EDTA)]- Diethylenetriaminepentaacetate (DTPA)
    • Forms multiple coordinate bonds with metal ions like Cd2+, Mg2+, etc.
    • Example: [Cd(DTPA)]2-

Slide 14 - Chelating Ligands

  • Chelating ligands are a type of polydentate ligands that form a ring structure called a chelate with the metal ion.
  • The formation of chelate rings increases the stability of the complex.
  • Example: Ethylenediaminetetraacetate (EDTA)

Slide 15 - Applications of Coordinate Compounds

  • Coordination compounds are widely used as catalysts in various chemical reactions.
  • They play a crucial role in industrial processes such as the Haber process for ammonia synthesis.
  • Some coordination compounds have therapeutic properties and are used in medicine.
  • Examples include cisplatin, a platinum-based coordination compound used in chemotherapy.

Slide 16 - Importance of Coordination Number

  • The coordination number of a metal ion in a coordination compound determines its chemical and physical properties.
  • It affects the stability, reactivity, and geometry of the complex.
  • Different coordination numbers result in different geometries such as square planar, tetrahedral, octahedral, etc.
  • Example: [Ni(CN)4]^2- has a square planar geometry with a coordination number of 4.

Slide 17 - Isomerism in Coordination Compounds

  • Coordination compounds exhibit different types of isomerism, including geometric isomerism and optical isomerism.
  • Geometric isomerism arises from the difference in spatial arrangement due to the restricted rotation around coordination bonds.
  • Optical isomerism occurs when a compound contains chiral ligands and lacks a plane of symmetry.
  • Example: [Co(en)2Cl2]Cl can exhibit geometric isomerism (cis and trans isomers).

Slide 18 - Crystal Field Theory

  • The Crystal Field Theory is used to explain the properties and colors of coordination compounds.
  • According to this theory, the interaction between the metal ion and the ligands generates a crystal field that splits the d orbitals of the metal.
  • This splitting leads to different energy levels and gives rise to color in coordination compounds.

Slide 19 - Ligand Substitution Reactions

  • Ligand substitution reactions involve the exchange of one or more ligands in a coordination compound.
  • These reactions can be either associative or dissociative.
  • In associative ligand substitution, a ligand approaches the metal ion before another ligand leaves the coordination sphere.
  • In dissociative ligand substitution, a ligand leaves the coordination sphere before a new ligand approaches the metal ion.

Slide 20 - Isomerism in Coordination Compounds

  • Coordination compounds exhibit different types of isomerism, including geometric isomerism and optical isomerism.
  • Geometric isomerism arises from the difference in spatial arrangement due to the restricted rotation around coordination bonds.
  • Optical isomerism occurs when a compound contains chiral ligands and lacks a plane of symmetry.
  • Example: [Co(en)2Cl2]Cl can exhibit geometric isomerism (cis and trans isomers).

Slide 21 - Coordination Compounds: Monodentate Ligands

  • Monodentate ligands have only one donor atom capable of forming a single coordinate bond with the metal ion.
  • Examples of monodentate ligands:
    • Ammonia (NH3)
    • Water (H2O)
    • Chloride ion (Cl-)
    • Bromide ion (Br-)
    • Iodide ion (I-)
  • Monodentate ligands have a coordination number equal to the number of ligands bonded to the metal ion.

Slide 22 - Coordination Compounds: Bidentate Ligands

  • Bidentate ligands have two donor atoms capable of forming two coordinate bonds with the metal ion.
  • Examples of bidentate ligands:
    • Ethylenediamine (en)
    • Oxalate ion (C2O4^2-)
    • Glycine (NH2CH2COOH)
    • 1,2-diaminopropane (NH2CH2CH2NH2)
    • Dimethylglyoxime ((CH3)^2C(NOH))2
  • Bidentate ligands increase the coordination number of the metal ion by two.

Slide 23 - Coordination Compounds: Polydentate Ligands

  • Polydentate ligands have multiple donor atoms capable of forming multiple coordinate bonds with the metal ion.
  • Examples of polydentate ligands:
    • Ethylenediaminetetraacetate (EDTA)
    • Diethylenetriaminepentaacetate (DTPA)
    • Nitrilotriacetate (NTA)
    • Triethylenetetraminehexaacetate (TTHA)
    • Acetylacetonate ion (acac-)
  • The coordination number in polydentate complexes depends on the number of donor atoms in the ligand.

Slide 24 - Coordination Compounds: Chelating Ligands

  • Chelating ligands are a subtype of polydentate ligands that form chelate rings with the metal ion.
  • The chelate ring increases the stability of the complex.
  • Examples of chelating ligands:
    • Ethylenediaminetetraacetate (EDTA)
    • 1,10-phenanthroline (phen)
    • Dimethylglyoximate ion (DMG^-)
    • Ethylenediamine-N,N’-diacetate (EDDA)
    • 2,2’-bipyridyl (bipy)

Slide 25 - Coordination Compounds: Stereoisomerism

  • Coordination compounds can exhibit different types of stereoisomerism.
  • Geometric isomerism arises due to the different spatial arrangement of ligands around the metal ion.
  • Optical isomerism occurs when a compound is chiral and lacks an internal plane of symmetry.
  • Examples of stereoisomers:
    • Geometric isomers of cis-diamminedichloroplatinum(II) and trans-diamminedichloroplatinum(II).
    • Optical isomers of [Co(en)3]^3+.

Slide 26 - Coordination Compounds: Color and Crystal Field Theory

  • The colors exhibited by coordination compounds can be explained by the Crystal Field Theory (CFT).
  • CFT describes the interaction between the metal ion and the ligands in terms of a crystal field.
  • The crystal field splits the d orbitals of the metal ion into different energy levels.
  • The energy difference between these levels corresponds to specific colors.
  • Example: The blue color of [Cu(H2O)6]^2+ and the pink color of [Co(H2O)6]^2+.

Slide 27 - Coordination Compounds: Ligand Substitution Reactions

  • Ligand substitution reactions involve the exchange of one or more ligands in a coordination compound.
  • These reactions can be either associative or dissociative.
  • Associative ligand substitution involves a new ligand approaching the metal ion before another ligand leaves.
  • Dissociative ligand substitution involves a ligand leaving before a new ligand approaches.
  • Examples of ligand substitution reactions:
    • [Cu(NH3)4]^2+ + 2H2O → [Cu(H2O)4(OH)]+ + 4NH3
    • [Co(NH3)6]^3+ + 3H2O ⇌ [Co(H2O)6]^3+ + 6NH3

Slide 28 - Coordination Compounds: Biocomplexes

  • Coordination compounds play a crucial role in biological systems.
  • Many essential biochemical processes involve coordination compounds.
  • Examples of biocomplexes:
    • Hemoglobin: Iron(II) heme complex that binds oxygen in red blood cells.
    • Chlorophyll: Magnesium(II) porphyrin complex involved in photosynthesis.
    • Vitamin B12: Cobalt(III) corrin complex involved in various metabolic reactions.

Slide 29 - Coordination Compounds: Catalysis

  • Coordination compounds are widely used as catalysts in various chemical reactions.
  • They can enhance reaction rates and improve selectivity.
  • Examples of catalytic processes involving coordination compounds:
    • Hydroformylation reaction (oxo process) using rhodium complexes.
    • Hydrogenation reactions using ruthenium, palladium, or platinum complexes.
    • Oxidation reactions using metalloporphyrin complexes.

Slide 30 - Coordination Compounds: Summary

  • Coordinate compounds are formed by the coordination of a central metal ion with one or more ligands.
  • Monodentate ligands have one donor atom, bidentate ligands have two, and polydentate ligands have multiple donor atoms.
  • Chelating ligands form ring structures called chelates.
  • Coordination compounds can exhibit stereoisomerism, including geometric and optical isomerism.
  • CFT explains the colors exhibited by coordination compounds.
  • Ligand substitution reactions involve the exchange of ligands in coordination compounds.
  • Coordination compounds have important applications in biocomplexes and catalysis.