1.

Explain the factors affecting the stability of the coordination compounds.

Answer»

Solution :The stability of a coordination compound depends upon the
FOLLOWING factors :
(1) Charge density of the central metal ION :
(i) The charge density is a ratio of the magnitude of the charge and
the radius of the metal ion.
(ii) Higher the charge density greater is the stability of the
complex.
(iii) For example the ionic radii of divalent ions `Cu^(2+) and Cd^(2+)` are
69 pm and 97 pm respectively hence charge density of `Cu^(2+)` ion is
higher than that of `Cd^(2+)`. Therefore the complex `[Cu(NH_(3))_(4)]^(2+)` is more
ions is,
`Cd^(2+) LT Mn^(2+)ltFe^(2+)ltCo^(2+)ltNi^(2+)lt Cu^(2+)`
(2) Nature of ligands : The ligands are Lewis bases since they
donate pairs of electrons to the central metal ion in the complex
forming coordinate bonds. Hence greater the basic strength of the
ligands more is the tendency to donate electrons hence greater is the
stability of the complex.
For example, `CN^(-)` is more basic than `NH_(3)`. Hence cyano complexes
of a metal ion are more stable than its ammine complexes.


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