Question

IUPAC name of Wilkinson's catalyst $[RhCl{(PP{H_3})_3}]$.
A. Chlorotris (triphenylphosphine) rhodium (I)
B. Chlorotris (triphenylphosphine) rhodium (IV)
C. Chlorotris (triphenylphosphine) rhodium (0)
D Chlorotris (triphenylphosphine) rhodium (VI)

Answer 1

The Wilkinson’s catalyst $[RhCl{(PP{H_3})_3}]$ is a coordination compound in which the central metal rhodium is surrounded by chloro ligand and triphenylphosphine ligand. The atom present in the ligand that is connected to the central atom is termed as the donor atom.

Complete step by step answer:
STEP 1: While naming the coordination compound, the name of the ligand is returned before the name of the central atom.
STEP 2: If more than one ligand is present, the arrangement of ligands is done in order: neutral, negative, and then positive. If ligands possess the same charge, then the ligands are arranged alphabetically.
STEP 3: The monodentate ligand with a number of occurrences has a prefix: mono, di, tri, tetra. The polydentate ligands have prefix bis-, tris- etc.
STEP 4: Name the central metal atom. If the central atom is an anion, it will have the suffix –ate.
STEP 5: Write the oxidation state of the metal atom with a Roman numeral.
The formula of Wilkinson’s catalyst is $[RhCl{(PP{H_3})_3}]$.
The ligand chloro is the anion and triphenylphosphine is a cation. So chloro is written before triphenylphosphine. As three triphenylphosphine is present, then the prefix is given as tris. The metal is rhodium. The oxidation state of rhodium is 1 and is given in the Roman numeral.
Thus, the IUPAC name of Wilkinson’s catalyst $[RhCl{(PP{H_3})_3}]$ is chlorotris (triphenylphosphine) rhodium (I).
Therefore, the correct option is A.

Note:
In $[RhCl{(PP{H_3})_3}]$, the arrangement of one chloro ligand and three triphenylphosphine ligand is in square planar geometry. The term PH stands for phenyl group. Wilkinson’s catalyst is used for the hydrogenation of alkenes.