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Date: 16/12/2021

Faculty Name : Mr. Mahesh K. Mahale

LMS user name : mahale.mahesh@mvpsvktcollege.ac.in

Course: S.Y.B.Sc. Chemistry

Year : Second

Semester: 3rd

Subject: Inorganic Chemistry

Unit : 2nd

Chapter name: Introduction to coordinator Compounds

Session name:

Asynchronous lecture no : 1

Intended date of publishing: 11/12/2021

Personal Information

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  • Introduction of Topic
  • Historical development of coordination compounds
  • Definition of various terms use in coordination chemistry

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Recap

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  • Coordinate bond and coordination number
  • Formation Constants: Inert and Labile complexes
  • Equilibrium constant for Formation of complexes

3

Session Agenda

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Students understand following points

  • Coordinate bond and coordination number
  • Thermodynamic and Kinetic stability
  • Equilibrium Constant
  • Nomenclature of Coordination complexes

Learning Objectives

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Coordinate or Dative bond:

  • Coordinate bond is a special type of covalent bond in which two shared electrons are contributed by only one of the two atoms linked together.
  • The coordinate bond is usually shown by a short arrow ( ) . The arrow head is directed from the donor atom to the acceptor atom.

Introduction to Coordination compounds

Definition of various terms involved in coordination chemistry:

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Introduction to Coordination compounds

Coordination number:

  • The number of monodentate ligands (i.e. The coordinated groups) which are directly attached to the central metal atom or ion is known as the coordination number of the metal atom /ion.
  • Example: [FeCl4]- and [FeCl6]3-

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Introduction to Coordination compounds

Coordination number (C.N.) = 4

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Introduction to Coordination compounds

Coordination number (C.N.) = 6

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Introduction to Coordination compounds

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Introduction to Coordination compounds

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Introduction to Coordination compounds

Formation constant

  • The number of monodentate ligands (i.e. The coordinated groups) which are directly attached to the central metal atom or ion is known as the coordination number of the metal atom /ion.
  • Example: [FeCl4]- and [FeCl6]3-
  • Generally two kinds of stability of complexes are considered during the study of the formation of complexes in solution. These are (i) Thermodynamic stability and (ii) Kinetic stability.

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Introduction to Coordination compounds

1) Thermodynamic stability:

  • It is a measure of the extent of formation of a complex under a given set of conditions at equilibrium.
  • It depends upon the strength of the metal ligand bond [M-L] in the complex.
  • Stronger the metal ligand bond, higher will be thermodynamic stability of the complex.

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Introduction to Coordination compounds

Kinetic Stability:

  • Kinetic stability is mainly concerned with rates and mechanism of chemical reactions and also with the energies involved in the formation of the activated complex.
  • In kinetic sense complexes are described in terms of inertness and lability. Many a times, these two groups of terms are used incorrectly. A stable

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Introduction to Coordination compounds

Here, Ni-CN bond is stronger than Ni-OH bond

More Stable

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Introduction to Coordination compounds

Equilibrium constant for Formation of complexes

The equilibrium constant K, of the above reaction can be written as,

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For such reactions, K is known as the formation constant or stability constant. If the value to K is high, the complex is stable.

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  • Coordinate bond and coordination number
  • Formation Constants: Inert and Labile complexes
  • Equilibrium constant for Formation of complexes

Summary

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  • Nomenclature of coordination Compounds (IUPAC)

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Precap