• Octahedral?complexes are formed when a central metal atom or ion forms?six coordinate bonds
• This could be six coordinate bonds with?six?small,?monodentate?ligands
  • Examples of such ligands are?water?and?ammonia?molecules and?hydroxide?and?thiocyanate?ions
  • As there are six ligands, these complexes are sometimes described as having?six-fold coordination

Table showing Examples of Common Monodentate Ligands

Example of an octahedral complex with monodentate ligands

• It could be six-coordinate bonds with?three?bidentate?ligands
  • Each bidentate ligand will form two coordinate bonds, meaning six-coordinate bonds in total
  • Examples of these ligands are?1,2-diaminoethane?and the?ethanedioate ion

Example of an octahedral complex with bidentate ligands

• It could be six-coordinate bonds with?one multidentate?ligand
  • The multidentate ligand, for example, EDTA4-,?forms all six-coordinate bonds

Example of an octahedral complex with a polydentate ligand

• The bond angles in an octahedral complex are 90o
• The?coordination?number?of a complex is the number of dative bonds formed between the central metal ion and the ligands
  • Since there are 6 dative bonds, the coordination number for the complex is 6