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NEET Chemistry Notes Coordination Compounds – Complex or Coordination Compounds

NEET Chemistry Notes Coordination Compounds – Complex or Coordination Compounds

Complex or Coordination Compounds

Complex or Coordination Compounds

Complex or coordination compounds are those molecular compounds which retain their identity in solid as well as in aqueous solution. In these compounds metal atoms are bound to a number of anions or neutral molecules by coordinate bonds. A part of these compounds is not dissociated in solution and its behaviour is different than its constituents.
NEET Chemistry Notes Coordination Compounds - Complex or Coordination Compounds 1
The following are same terms related to coordination compounds given as: Definitions of some important terms pertaining to coordination compounds

Complex Ion

It is an electrically charged species in which central metal atom or ion is surrounded by number of ions or molecules.
NEET Chemistry Notes Coordination Compounds - Complex or Coordination Compounds 2
Homoleptic and Heteroleptic Complexes

Complexes in which a metal is bound to only one kind of donor groups, e.g.. [Co(NH3)6]3+ are known as homoleptic. Complexes in which a metal is bound to more than one kind of donor groups, e.g.. [Co(NH3 ) 4Cl2 ]+,  are known as heteroleptic.

Ligands

The ions or molecules bound to the central atom/ion in the coordination entity are called ligands.

Types of Ligands

    1. Unidentate Ligand It is bound to a metal ion through a single donor atom.
      NEET Chemistry Notes Coordination Compounds - Complex or Coordination Compounds 6
  1. Didentate of Bidentate Ligand It is bound to a metal ion through two donor atoms.
    NEET Chemistry Notes Coordination Compounds - Complex or Coordination Compounds 3
  2. Polydentate It is bound to a metal ion through several donor atoms, e.g. ethylene diamine tetraacetate ion [EDTA]4-.
  3. Ambidentate Ligands It can ligate through two different atoms,e.g. —N02,—ONO, —SCN,—NCS
  4. Chelate Ligands may be di or polydentate ligands which form closed ring with central metal ion. Closed ring is known as chelate ring and this process is called chelation.
    More the number of chelate rings in a complex, complex will be more stable. The number of such ligating groups is called the denticity.

Coordination Number

The number of chemical bonds formed by the ligands with central metal atom or ion is called the coordination number of that complex.

Coordination Sphere

The central ion and the ligands attached to it are enclosed in square bracket which is known as coordination sphere. The ionisable group written outside the bracket is known as counter ions.

 Coordination Polyhedron

The spatial arrangement of the ligands which are directly attached to the central atom or ion, is called coordination polyhedron around the central atom or ion. e.g. [Co (NH3)6]3+ is octahedral [Ni (CO)4] is tetrahedral

Oxidation Number of Central Atom

The charge of the complex if all the ligands are removed along with the electron pairs that are shared with the central atom, is called oxidation number of central atom.
e.g. onidation number of copper in [Cu(Cv)4]3- is + 1 and it is writen as Cu(I).

Magnetic Properties

The given complex compound is paramagnetic if one or more unpaired electrons are present in the d-subshell. If the complex does not contain any unpaired electron, is diamagnetic.
Magnetic moment,NEET Chemistry Notes Coordination Compounds - Complex or Coordination Compounds 4

Shapes

Shapes of coordination compounds depend upon hybridisation present in them
NEET Chemistry Notes Coordination Compounds - Complex or Coordination Compounds 5

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