Chapter 22, Problem 22.85QP

Interpretation Introduction

Interpretation:

A $C{o}^{2+}$ complex of octahedral geometry absorbs in blue region of visible spectrum. The complex is whether low-spin or high-spin has to be determined.

Concept Introduction:

Complexes are of two types - low spin complex and high spin complex. A complex is said to be low-spin if it doesn't have unpaired electrons whereas in high spin complex there will be presence of unpaired electrons.

Almost all the Co-ordination compounds are colored compounds.  Presence of unpaired electrons in a complex compound makes it colored as the unpaired electrons undergo transition from lower energy level to higher energy level.  The color of the complex observed is complementary to the color absorbed in the wavelength region.