Introduction:
The IUPAC name of the compound Na[Mn(CO)5] is Sodium Pentacarbonylmanganate.

Explanation:
The IUPAC name of a compound is derived from its chemical formula, which provides information about the elements and their arrangement within the compound. Let's break down the name and explain each part in detail.

Sodium (Na):
The first part of the name, "Sodium," refers to the metal present in the compound. Sodium is an alkali metal with the symbol Na in the periodic table.

Pentacarbonylmanganate:
The second part of the name, "Pentacarbonylmanganate," describes the coordination complex formed by the metal and ligands. Here is a breakdown of this part:

Penta:
The prefix "penta" indicates that there are five ligands attached to the central metal atom.

Carbonyl (CO):
The ligands in this compound are carbonyl groups, represented by the CO symbol. Each carbonyl ligand consists of a carbon atom bonded to an oxygen atom.

Manganate:
The term "manganate" indicates that the central metal atom is manganese (Mn). Manganese is a transition metal with the symbol Mn in the periodic table.

The overall structure:
The compound Na[Mn(CO)5] consists of a sodium cation (Na+) and a pentacarbonylmanganate anion ([Mn(CO)5]-). The sodium cation is positively charged, while the pentacarbonylmanganate anion carries a negative charge to maintain overall neutrality.

Summary:
In summary, the IUPAC name of Na[Mn(CO)5] is Sodium Pentacarbonylmanganate. The name indicates the presence of sodium as the metal and a coordination complex with five carbonyl ligands attached to a central manganese atom. The IUPAC naming system provides a standardized way to describe chemical compounds, allowing scientists to communicate effectively and unambiguously about their structures and compositions.