122. Briefly write the rules for writing the formulas of mononuclear coordination compounds.

Mononuclear coordination compounds are the complex ions which have only one central metal atom or ion.

The formula of such complex compounds are written as per of the following rules:

(i) Central atoms is written first.

(ii) It is followed by the symbols of the ligands which are written in the order-negative ligands, neutral ligands followed by positive ligands.

(iii) If more than one type of ligands are there then their formulae are written according to the alphabetical order of the first symbol of their formulae.

(iv) The number of ligands linked to metal atom are indicated by putting its number as subscript written after simple brackets in which the lingands are placed.

(v) The coordination sphere is enclosed in square brackets.

(vi) No space is kept between representations of ions in the formula, whether the coordination sphere is a cation or anion.

(vii) If the formula of coordination sphere is written without the counter ion then the charge on the coordination sphere is written as a superscript on the right hand side, outside the square brackets, e.g., [Co(NH₃)₆]Cl₃, [Cr(H₂O)₆]³⁺ etc.