Definitions of some terms related to Coordination Compounds Preparation and Properties

Definitions of some terms related to Coordination Compounds Preparation and Properties

Definition of Some Terms Related to Coordination Compounds :

→ Ambidentate Ligand : Ligands which can ligate (link) through two or more different donor atoms present in it are called ambidentate ligand. Although at a time only one atom can link with central metal atom.

Example : NO2, and SCN NO2 can link through N as well as O while SCN can link through S as well as N atom.

Definitions of some terms related to Coordination Compounds Preparation and Properties 1

→ Chelate Ligand : Polydentate ligands use their one or more donor atoms to from co-ordinate bond with central metal so as to give a ring like structure. This ring is called chelate ring and the ligand is called chelate ligand.

Definitions of some terms related to Coordination Compounds Preparation and Properties

Example : Ethylenediammine and oxalato ion etc.

Definitions of some terms related to Coordination Compounds Preparation and Properties 2

→ Co-ordination Number : It is defined as the total number of coordinate bonds formed by central metal atom with the ligands. For example, the co-ordination number of cobalt in [Co (NH3)4]3+ is 4.

→ Similarly, the co-ordination number of Ag+ in [Ag(NH3)2]+ is 2, that of Cu2+ in [Cu(NH3)4]2+ is 4, and that of Fe3+ is [Fe(CN)6]3- is 6.

Example :

[Ag(NH3)2]Cl C.N. = 2 [Cu(NHa)4]S04 C.N. = 4
[Fe(NH3)6]Cl3 C.N. = 6 [Ni(en)*]Cl9. C.N. = 4
Na[Co(ox)3] C.N. = 6 Na2 [Co(acac)2Cl2] C.N. = 6
[Co(dien)2] C.N. = 6 [Co(EDTA)]-2 C.N. = 6

→ The most common coordination number exhibited by metal ions are 2, 4 and 6.

Definitions of some terms related to Coordination Compounds Preparation and Properties

Familier coordination number of some common metal ions :

Definitions of some terms related to Coordination Compounds Preparation and Properties 3

→ Coordination number of metal ion is responsible for geometry of complex.

  • C.N. = 2 → Linear
  • C.N. = 3 → Triangular planar
  • C.N. = 4 → Tetrahedral or square planar
  • C.N. = 5 → Triangular bipyramidal
  • C.N. = 6 → Octahedral

Chemistry Notes