Question

The IUPAC name for the complex compound $Li\left[ Al{{H}_{4}} \right]$ is:
(A) Lithium aluminium hydride
(B) Hydride aluminium lithium (III)
(C) Lithium tetrahydridoaluminate (III)
(D) Lithium tetrahydridoaluminate (I)

Answer 1

The IUPAC name for the complex compounds has a specific pattern and contains the word root of all the elements comprising the complex compound.

Complete step by step solution:
Let us first understand the coordination complex and the procedure to name any complex before we move towards the given data.
Coordination complex –
Coordination compounds are any class of substances with chemical structures which have a central metal atom surrounded by ligands (nonmetal atoms or groups of atoms) joined by chemical bonds.
The central atom is called the coordination centre.
Ligands or complexing agents is an array of bound molecules or ions.
Coordination complexes are mostly metal-containing compounds, those are transition metals.
The basic procedure for naming a complex is as follows;
1. While naming a complex ion, the ligands are named prior to the metal ion.
2. The ligands’ names are given in alphabetical order. Numerical prefixes do not affect the order.
- Monodentate ligands receive di-, tri-, tetra-, penta-, or hexa- as prefix according to their number of occurrences.
- Multiple occurring polydentate ligands receive bis-, tris-, tetrakis-, etc.
- Anions end in o. this replaces the final ‘e’ when the anion ends with ‘-ide’, ‘-ate’ or ‘-ite’, example- chlorine becomes chlorido and sulphate becomes suphato.
- Neutral ligands are given their common name, with some exceptions: $N{{H}_{3}}$ becomes amine, ${{H}_{2}}O$ becomes aqua or aquo, CO becomes carbonyl, NO becomes nitrosyl.
3. Write the name of the central atom/ion. The central atom’s name will end in ‘-ate’, if the central atom is an anion. Except for mercury, other atoms will get their respective Latin name.
4. The oxidation state of the central atom is to be specified enclosed in parentheses. Those should be in roman numerals.
5. Name of the cation should be preceded by the name of the anion.
Illustration-
$Li\left[ Al{{H}_{4}} \right]$ would be named as;
$Li\left[ Al{{H}_{4}} \right]$- Lithium aluminium hydride, commonly abbreviated as LAH, is a chemical compound with the chemical formula $Li\left[ Al{{H}_{4}} \right]$.
The name of the counter ion is lithium thus, we write the name of the complex ion. Also, contains aluminium (III). The anion is present here so, tetrahydrido would be added.
Therefore, the IUPAC name of $Li\left[ Al{{H}_{4}} \right]$ will be Lithium tetrahydridoaluminate (III).

Hence, option (C) is correct.

Note: The preferred IUPAC name of $Li\left[ Al{{H}_{4}} \right]$ is Lithium tetrahydridoaluminate (III), otherwise other common names are-
Systematic IUPAC name- Lithium aluminide
-Other names- Lithium aluminium hydride, Lithium alanate, Lithium aluminohydride, Lithium tetrahydridoaluminate, Lithal.
-So, do not get confused while answering the question. Always prefer the preferred IUPAC name.