The formula of tetrachlorodiammineplatinum(IV), is (a) \(\left[\mathrm{Pt}\left(\mathrm{NH}_{3}\right)_{2}\right] \mathrm{Cl}_{4}\) (b) \(\left[\mathrm{Pt}\left(\mathrm{NH}_{3}\right)_{2} \mathrm{Cl}_{4}\right]\) (c) \(\left[\mathrm{Pt}\left(\mathrm{NH}_{3}\right)_{2} \mathrm{Cl}_{2}\right] \mathrm{Cl}_{2}\) (d) \(\mathrm{K}_{4}\left[\mathrm{Pt}\left(\mathrm{NH}_{3}\right)_{2} \mathrm{Cl}_{4}\right]\)

Chemical nomenclature is the systematic naming of chemical compounds and is a critical aspect of chemistry. It allows chemists to communicate unambiguously about chemical substances. Key rules and conventions are used for naming coordination compounds, which are complexes made up of a central metal atom or ion bonded to ligands (molecules or ions that donate at least one electron pair to the metal to form a coordinate bond).

In coordination compounds, the ligands are listed first in a formula, followed by the metal with its oxidation state in Roman numerals (e.g., platinum(IV)). Prefixes such as 'di-', 'tri-', or 'tetra-' indicate the number of identical ligands. The formula is then enclosed in square brackets when referring to a complex ion. For neutral complexes, the square brackets are used but not essential.

For example, the name tetrachlorodiammineplatinum(IV) breaks down into 'tetra-' for four chlorides, 'diammine' for two ammonia ligands, and 'platinum(IV)' showing platinum with a +4 charge. Thus, understanding the name of the compound provides valuable clues to its structure and formula.

Complex ions form part of a broader group of chemistry called complex compounds or coordination compounds. They consist of a metal center surrounded by molecules or ions called ligands. These ligands are capable of 'coordinating' with the metal, typically through lone pairs of electrons.

In the case of tetrachlorodiammineplatinum(IV), platinum acts as the central metal ion while ammonia (NH3) and chloride ions (Cl-) serve as ligands. Coordination compounds can have different configurations and number of ligands, which are reflected in their chemical formulas. The formula within the square brackets represents the coordination sphere, which displays the direct bonding of ligands to the central metal ion.

The coordination number (the total number of attachment sites occupied by ligands) plays a significant role in the geometry and properties of the complex. For instance, with six ligands, an octahedral shape is common, though our example compound has different stoichiometry. The strength and type of ligands also influence the stability and reactivity of the complex ion.

The oxidation state, or oxidation number, is a concept used in chemistry to indicate the degree of oxidation of an atom in a chemical compound. Oxidation states can be positive, negative, or zero, and they are essential for balancing chemical equations and understanding redox reactions.

In coordination chemistry, the metal's oxidation state affects how the ligands are bonded and is written as a Roman numeral in the chemical name. For example, in tetrachlorodiammineplatinum(IV), the (IV) indicates that platinum has an oxidation state of +4. By knowing the oxidation states of the metal and ligands, we can deduce the proper chemical formula.

Oxidation states also play a crucial role in determining the number of ligands needed to balance the charge in a complex ion. Neutral ligands like NH3 do not affect the oxidation state. However, negatively charged ligands such as Cl- do. Thus, to maintain charge neutrality, the number of negatively charged ligands must account for the positive charge contributed by the central metal ion. Overall, understanding oxidation states is fundamental in predicting the formation and charge of complex ions.