2 LIGANDS & COMPLEX IONS

• What are the two main components of a complex in transition element chemistry?

  Central metal ion and ligands
• What is a ligand in the context of transition metal complexes?


  A ligand is a molecule or ion that donates an electron pair to form a co-ordinate bond with a transition metal.
• How does a ligand act as a Lewis base?

  It acts as an electron pair donor.
• What charge do ligands typically have?

  Ligands have a negative charge or a lone pair of electrons capable of being donated.
• What is the role of a ligand in a complex?

  A ligand acts as a nucleophile in a complex.
• How many dative bonds can ligands form with a central metal ion?

  Ligands can form different numbers of dative bonds to the central metal ion.
• What is a monodentate ligand?

  A monodentate ligand forms one dative bond to the central metal ion.
• What is a bidentate ligand?

  A bidentate ligand forms two dative bonds to the central metal ion.
• What is a multidentate ligand?

  A multidentate ligand forms multiple dative bonds to the central metal ion.
• What does the coordination number represent?

  The coordination number is the number of co-ordinate bonds to the central metal atom/ion.
• What are some examples of ligands?

  • Water (H2O)
  • Ammonia (NH3)
  • Chloride (Cl–)
  • Cyanide (CN–)
  • Hydroxide (OH–)
  • Ethanedioate (C2O4 2–)
  • 1,2-diaminoethane (H2NCH2CH2NH2)
• What is the shape of six-coordinate complexes?

  Six-coordinate complexes have an octahedral shape.
• What is the bond angle in an octahedral complex?

  The bond angle in an octahedral complex is 90 degrees.
• What is the shape of four-coordinate complexes?

  Four-coordinate complexes can be tetrahedral or square planar.
• What is the bond angle in a tetrahedral complex?

  The bond angle in a tetrahedral complex is 109.5 degrees.
• What is the bond angle in a square planar complex?

  The bond angle in a square planar complex is 90 degrees.
• Which ligand is usually associated with square planar complexes?

  Cyanide ions (CN–) are usually associated with square planar complexes.
• What is an example of a square planar complex?

  An example of a square planar complex is cisplatin.