oxidation state of binuclear coordination compounds

Coordination complexconsists of a central atom or ion, which is usually metallic and is called thecoordination centre, surrounded by molecules or ions, known asligandsor complexing agents.he central metal ion plus the attached ligands of a coordination compound is called the coordination sphere.
1. For neutral coordination complexes: The sum of charges on the ligands and the central metal atom is equal to Zero.
2. For positively charged coordination complexes: The sum of charges on the ligands and the central metal atom is equal to charge on the coordination sphere.
3. For negatively charged coordination complexes : The sum of charges on the ligands and the central metal atom is equal to charge on the coordination sphere.
To find the oxidation numbers, you must consider the charge that each ligand attached to the metal carries and the overall charge of the compound itself inside the brackets.
examples,1.In case of [Cu(NH3)4]2+, say oxidation state of Copper = x and we know that charge on ligand NH3 = 0.
So, x + ( 0 )x4 = +2
x = +2
So Cu must have an oxidation state of II (2+).
2. In case of [Fe(CN)6]4-, say oxidation state of Iron = x and we know that charge on ligand CN = -1.
So, x + (-1)x6 = -4
x = +2
So Fe must have an oxidation state of II (2+).