CHARGE TRANSFER

COLOR OF COMPLEXES

SHOBANA.N.S

QUEEN MARY’S COLLEGE

INTRODUCTION

• Colour provides a vital enhancement to the world in which we live.

• Every day materials we use - textiles, paints, plastics, paper, and foodstuffs - are especially appealing if they are colourful.

ABSORPTION OF LIGHT

COLOR OF TRANSITION COMPLEXES

• DUE TO:

1. d-d transition

2. charge transfer

3. Spin allowed transition

CHARGE TRANSFER

WHAT DOES CHARGE -TRANSFER MEAN ??

Usually charge refers the charge of electron, which is being transferred within the molecular entity.

Four types of charge transfer complexes are known :

1. LIGAND TO METAL CHARGE TRANSFER

2. METAL TO LIGAND CHARGE TRANSFER

3. METAL TO METAL CHARGE TRANSFER

4. LIGAND TO LIGAND CHARGE TRANSFER

LIGAND TO METAL CHARGE TRANSFER COMPLEXES

1. Presence of pi donor ligands:

F-, Cl, Br-, I-, H2O, OH-, RS-, S2-, NCS-, NCO.

2. Metal ions are devoid of d- electrons.

CONDITION

METAL TO LIGAND CHARGE TRANSFER COMPLEXES

1. Presence of pi accepting ligands

CO, NO, CN-, N2, bipy, phen, RNC, C5H5-, C=C,

C=C

2. Metal in 0,+1,+2 oxidation states ( low oxidation

state).

CONDITION

Tris(bipyridine)ruthenium(II)

dichloride

[Ru(bpy)3]Cl2.

SPECTRA

KMnO4 SpectraLMCT

MLCTTris(bipyridine)ruthenium(II) dichloride

THANK YOU !!!