the coordination sphere. The other associated ion K + is called the counter ion. Coordination polyhedron: The three dimensional spacial arrangement of ligand atoms/ions that are directly attached to the central atom is known as the coordination polyhedron (or polygon). For example, in K [Fe(CN) ], the coordination polyhedra is octrahedral.
The coordination polyhedra of [Ni(CO) ] is tetrahedral. Coordination number: The number of ligand donor atoms bonded to a central metal ion in a complex is called the coordination number of the metal. In other words, the coordination number is equal to the number of σ-bonds between ligands and the central atom. For example, i.
In K [Fe(CN) ], the coordination number of Fe + is . ii. In [Ni(en) ]Cl , the coordination number of Ni + is also . Here the ligand 'en' represents ethane- , -diamine (NH -CH -CH -NH ) and it contains two donor atoms (Nitrogen) Each ligand forms two coordination bonds with nickel.
So,totally there are six coordination bonds between them. Oxidation state (number): The oxidation state of a central atom in a coordination entity is defined as the charge it would bear if all the ligands were removed along with the electron pairs that were shared with the central atom. In naming a complex, it is represented by a Roman numeral. For example, in the coordination entity [Fe(CN) ] - , the oxidation state of iron is represented as (II).
The net charge on the complex ion is equal to the sum of XII U5 Coordination XII U5 Coordination - - - - the oxidation state of the central metal and the charge the on the ligands attached to it. Using this relation the oxidation number can be calculated as follows Net charge = (oxidation state of the central metal) + [(No. of ligands) X (charge on the ligand)] Example : In [Fe(CN) ] - , let the oxidation number of iron is x : The net charge: - = x + (- )