The Monds method is a process used to prepare volatile metal carbonyls, and it involves the reaction of a metal with carbon monoxide gas. In this method, the central atom in the stable volatile complex formed has an oxidation number of 0.

Explanation:
- The Monds method involves the reaction of a metal with carbon monoxide gas under specific conditions. The metal used is usually a transition metal such as nickel, iron, or cobalt.
- When the metal reacts with carbon monoxide, a complex is formed in which the metal is surrounded by carbon monoxide ligands. The ligands are bonded to the metal through a coordinate covalent bond, where the ligand donates a pair of electrons to the metal.
- In the stable volatile complex formed in the Monds method, the central atom is in a zero oxidation state. This means that the central atom has neither gained nor lost any electrons and has an equal number of electrons in its valence and core orbitals.
- The zero oxidation state of the central atom in the complex is due to the electron-donating nature of the carbon monoxide ligands. The carbon monoxide ligands are strong π-acceptor ligands, meaning they can accept electron density from the metal center, resulting in a decrease in the oxidation state of the metal. This electron donation from the ligands compensates for the positive charge on the metal, resulting in a zero oxidation state for the central atom.
- The stable volatile complex formed in the Monds method is important because it can be used as a precursor for the synthesis of various organometallic compounds. These organometallic compounds are widely used in catalysis, as well as in the production of pharmaceuticals, polymers, and other industrial chemicals.
- Overall, the central atom in the stable volatile complex formed in the Monds method has an oxidation number of 0 due to the electron-donating nature of the carbon monoxide ligands.