The correct IUPAC name of [PtBr₂(PMe₃)₂] is :

Solution

Chemistry ma’am · 5 steps

Order the ligands alphabetically, then use bis for a ligand whose name already has a number in it.

1. Find the ligands. There are two Br⁻ ligands, named bromo (bromido in the newest rules). There are also two neutral P(CH₃)₃ ligands, named trimethylphosphine.
2. Alphabetical order. Ligands are listed alphabetically by their own names, ignoring counting prefixes like di or bis. The b of bromo comes before the t of trimethylphosphine, so bromo goes first. The tri in trimethylphosphine is part of the ligand's name, so it does count for alphabetising.
3. Choose the prefix. For a simple ligand like bromo, two of them is di: dibromo. Trimethylphosphine already contains the prefix tri, so its count uses bis with the name in brackets: bis(trimethylphosphine).
4. Metal and charge. The complex is neutral, so the metal keeps its plain name, platinum. Each Br⁻ gives -1 and PMe₃ gives 0, so x - 2 = 0 and Pt is +2, written (II).
5. So. The name is dibromobis(trimethylphosphine)platinum(II), which is option (c).

The idea to keep. Alphabetise ligands by their names, never by di, tri, bis or tris. Use bis, tris for ligands whose names already contain a number or are complex, and put the name in brackets.

Answer from the NTA final answer key. Solution by PrepWiser.