Page 42 - 6273

LECTURE 5. COORDINATION COMPLEXS

PROGRAM QUESTIONS:

5 .1 COORDINATION COMPLEXS

5.2 NOMENCLATURE OF COMPLEX COMPOUNDS

5.1 Coordination complexes
Coordination complexes are compounds created without the new electronic pairs

formation.

There are internal and external spheres in coordination complexes. The

internal sphere, or complex, consists of a central atom (complexing agent) and

ligands that are located (coordinated) around it. The ions that are not a part of the

inner sphere form the outer sphere of the coordination complex.

Central atoms in coordination complexes are mostly positively charged ions

or atoms of d-metals, rarely - s- and p-metals. Some nonmetals (B, Si, N, P) can

also be complexing agents.

2-
-
2-
-
-
-
Ligands are mostly simple (Cl , Br , I ) or complex (CO 3 , S 2O 3 , NO 2 ) ions,
neutral molecules (in most cases they are polar) both inorganic (H 2O, NH3, CO)
and organic (NH 2CH 2NH 2, C 2H 5NH 2).
The number of places in the inner sphere of the complex that may be occupied

by ligands is called the coordination number (CN) of the complexing agent. The

value of coordination numbers is within the range from 1 to12.

Coordination complexes may contain both a complex anion and a complex

cation, or a complex non-charged particle. Therefore these compounds are named

according to the particular rules.

5.2 Nomenclature of complex compounds

42