Question

The IUPAC name of the Wilkinson's catalyst $[RhCl{(P{Ph}_{3})}_{3}]$ 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 naming of the coordination compound provides a method to represent and describe the names and formulas of coordination compounds systematically. The given compound is also named with reference to the rules set up by IUPAC.

Complete step by step answer:
The rules of complex nomenclature are given below:
Rule 1: While writing the name of a complex compound, we always name the cation before the anion.
Rule 2: When there are multiple types of ligands present in any coordination compound,
We name them in alphabetical order after the name of central metal atom/ion.
Name of the anionic ligands ends with ‘o’.
For neutral ligands, their common name is used.
Rule 3: If the names of the ligands have a numerical prefix, then we use the terms like bis, tris, tetrakis.
Rule 4: After naming the ligand in alphabetic order, we name the central metal atom/ion.
- If the complex ion is a cation, we name the metal the same as the element.
- If the complex is an anion, the name of metal ends with the suffix -ate for Latin name.
Rule 5: We give the oxidation state of the metal in the complex as a roman numeral in parentheses.
Rule 6: We name the neutral complex molecule similar to that of the complex cation.

Now let us look at the question given to us. The ligand present is $Cl{(P{Ph}_{3})}_{3}$. So to start the naming, we start in the alphabetical order, Therefore, the IUPAC naming of the ligand is chlorotris(triphenylphosphine). In this, 'triphenylphosphine' is given because the phosphorus is attached to 3 phenyl molecules and the 'tris' is used to represent the 3 molecules of triphenylphosphine attached to the chlorine atom. Now moving onto the metal, rhodium is in +1 oxidation state. Therefore, the IUPAC name of the complex compound is Chlorotris (triphenylphosphine) rhodium (I). Hence, the option (a) is the correct answer.

Note: Wilkinson’s Catalyst is a coordination compound whose coordination centre is rhodium. It is extensively used as a catalyst in the hydrogenation of alkenes. At ambient temperatures, this coordination complex exists as a reddish-brown solid.