Question

The IUPAC name of the Wilkinson’s catalyst $[RhCl{{(PP{{h}_{3}})}_{3}}]$ is:
(A) Chlorotris (Triphenylphosphine ) rhodium (I)
(B) Chlorotris (Triphenylphosphine ) rhodium (IV)
(C) Chlorotris (Triphenylphosphine ) rhodium (0)
(D) Chlorotris (Triphenylphosphine ) rhodium (VI)

Answer 1

Hint: The IUPAC nomenclature is a method of naming organic chemical compounds as per the rules given by the International Union of Pure and Applied Chemistry. IUPAC names give an unambiguous and absolute definition to a compound.

Complete step by step answer:
The systematic name of a compound is derived from its structural formula by applying IUPAC rules which are given below:
Rule 1: While writing the name of a complex compound, we start by naming the cation first followed by the naming of the anion.
Rule 2: When there are multiple ligands present in a coordination compound, the following order is followed: neutral, negative, positive. If there are multiple ligands of the same charge type, they are named in alphabetical order.
Rule 3: Multiple occurring ligands are named by using prefix di-, tri-, tetra-, Penta-, Hexa-. Polydentate ligands receive bis-, tris-, tetrakis-, etc as a prefix.
Rule 4: Anions that end in -ido, the final “e” is replaced by “ate”.
Rule 5: Neutral ligands are given their usual names with some exceptions like $N{{H}_{3}}$becoming ammine, ${{H}_{2}}O$ becoming aqua, CO becoming carbonyl, NO becoming nitrosyl.
Rule 6: If the central metal atom’s oxidation state needs to be specified, write it as a Roman numeral in parentheses.

Now let us look at the question given to us.
The ligands present are $Cl{{(PP{{h}_{3}})}_{3}}$. So we start by naming the ligand. The ligand after following the IUPAC rules is named as chlorotic(triphenylphosphine) because the phosphorus is attached to 3 phenyl molecules. The prefix ‘tris’ is used to represent the 3 molecules of triphenylphosphine attached to the chlorine atom. The metal Rhodium in the +1 oxidation state is present in the complex.

Therefore as we can see that the IUPAC name of Wilkinson’s catalyst $[RhCl{{(PP{{h}_{3}})}_{3}}]$ is Chlorotris (Triphenylphosphine ) rhodium (I). Thus, option A is the correct one.

Note: Wilkinson’s catalyst has a square planar coordination geometry with a molar mass of 925.22 grams/mole. It’s melting point lies between 518 to 523 K. Wilkinson’s catalyst can be prepared by reacting hydrated rhodium(III) chloride with an excess of triphenylphosphine in the presence of ethanol. Wilkinson’s catalyst is used to reduce a single alkene on a molecule, but typically it is used when there are multiple alkenes present in the compound and we want to selectively reduce the alkenes.