IUPAC Nomenclature of Mononuclear Co-Ordination Compounds

IUPAC stands for the International Union of Pure and Applied Chemistry. The IUPAC is an international body that represents scientists in chemistry and was established in 1919. They are responsible for creating a common language in chemistry so that chemists from across the world can communicate without confusion.

The IUPAC is in charge of deciding how chemicals are named, i.e. chemical nomenclature and terminology. They decide how new elements are named in the periodic table, standard methods for measurements, atomic weights, and other scientifically evaluated data. They do this by creating a committee to assign rules that must be followed while deciding on a name for a compound. 

The IUPAC is also involved in other activities like publishing technical reports, journals, books, databases, and other information that helps researchers and scientists in their research work. 

IUPAC Nomenclature Rules of Mononuclear Coordination Compounds:

These are some of the rules set by the IUPAC in naming mononuclear coordination compounds:

• When naming mononuclear coordination compounds, the name of the cation should come first, followed by the name of the anion. NaCl, for example. This rule is applicable even if the cation/anion is not complex.
• For complex ions, the name of the ligand is written first, and then the central metal atom is named. However, this rule is reversed when a chemical formula is written.
• Ligands  name ends with the letter O if the ligand is negative For example: Chloro for Cl-, Cyano for CN-, and Hydrido for H‑. On the other hand, the name remains unmodified for neutral ligands. For instance: methylamine for MeNH2.
• Some ligands have unique names, like aqua for water, ammine for ammonia, carbonyl for carbon monoxide, and nitrosyl for nitrogen monoxide.
• Greek prefixes are used to indicate numbers: mono for one, di for two, tri for three, tetra for four, penta for five, and so on. However, if the ligand has a numeric name like triphenylphosphine, then di, tri, tetra are skipped, and alternative prefixes like bis, tris, tetrakis are used instead.
• Two systems are followed for writing oxidation states or the charge on the compound:
  
  
  • The Stock System: Roman numerals are used in parenthesis after the name of the metal ion.
  • The Ewing-Basset system: The charge of the metal ion is placed in parenthesis, followed by the name of the metal ion.
• Roman numbers or zero in parentheses are used to indicate the oxidation state of the central metal atom.
• If the complex ion is negative, then the name of the metal ends with -ate. For example, nickelate, cuprate, ferrate, cobaltate, etc.
• If more than one ligand is present in the complex, then the ligand is named in alphabetical order irrespective of the number of ligands present in the complex. Therefore, NH3 would be considered an ammine and written before chloro (Cl-).
• Some metals and anions have unusual names too. B is borate, Au is aurate, Ag is argentite, Fe is ferrate, Pb is Plumbate, Cu is cuprate, Sn is stannate, etc.
• Square brackets are used to enclose a complex ion or a neutral coordination species.

Naming a complex according to IUPAC nomenclature rules

Consider the IUPAC name of the complex K3[Cr(C2O4)3].3H2O. It will be named by following these steps.

1. Identify the central metal. Here the central metal atom is Chromium.
2. Identify the oxidation state. Here the oxidation state is (III).
3. Identify the electronic configuration. Here it is d3.
4. Identify the coordination number. Here it is 6 because three bidentate ligands are present in the above complex.
5. Identify the shape of the complex. This one is octahedral.

Thus, following IUPAC nomenclature rules, the name of this compound will be potassium tris(oxalate)chromate (III) trihydrate.

IUPAC Names for Ligands

Given below is a table with the names of some of the ligands following IUPAC nomenclature rules.

IUPAC Names for Anionic Ligands

IUPAC Names for Neutral Ligands

IUPAC Names for Metals

The IUPAC names of some of the metals when found in anionic complexes are:

IUPAC Names for Mononuclear Coordination Compounds

Here are the names of some mononuclear coordination compounds following IUPAC nomenclature rules.

 IUPAC Names of Acids

The IUPAC has set different rules for naming acids. Acids are named after the anion they form when they dissolve in water. Acids will have various names depending upon which anion is formed. 

Simple acids or binary acids have one hydrogen and one anion. Their names usually end with -ide. They also use the prefix -hydro, followed by the first syllable of the acid and then the suffix “ic.” Following these rules, HCl – which contains hydrogen and chlorine – will be called hydrochloric acid according to IUPAC naming rules.

Complex acids have oxygen and follow more detailed rules. Some of these are as follows:

1. According to the IUPAC, acids having -ate in their anionic form will use the suffix -ic. For example, HNO3 is called nitric acid.
2. If a polyatomic ion with more than one oxygen is present, the suffix -ic will be used instead of -ate. For example, HClO4 contains the chlorate ion ClO3-. It will, therefore, be called perchloric acid.
3. If there are two oxygen atoms, then -ate will be replaced by -ous in the suffix. For example, HClO2 will be called chlorous acid.
4. If there are three or more oxygen atoms in the compound, the prefix hypo- is used along with the suffix -ous. For example: instead of bromic acid, HBrO3 will be hypobromous acid,HBrO.

Here is a table containing the names of some acids, including acetic acid, following IUPAC nomenclature rules.

Conclusion:

The IUPAC is an organisation responsible for making rules for naming compounds. Their responsibility is to ensure that scientists worldwide can understand each other without confusion by following these standard naming rules. 

This ensures that compounds are named following the same rules and helps all scientists, researchers, professors, and students understand which compound is being discussed. IUPAC naming rules change based on the nature of the compound as well. 

Like coordination compounds, other types of compounds also follow different rules. Other acids, alcohol, bases, aldehyde, and ketonic groups all have their own rules that must be followed while being named. While some of the mononuclear coordination compounds and IUPAC names and some IUPAC names of acids are mentioned in these tables, many names must be individually calculated and arrived at.