[NiCl_2(PPh_3)_2] is named as:

The correct answer is Option (1) → Dichloridobis (triphenyl phosphine) nickel (II)

IUPAC rules for a neutral complex:

• Ligands are named first, in alphabetical order: chlorido (\( \ce{Cl^{-}} \)) before triphenylphosphine (\( \ce{PPh3} \)).

• Two chlorido ligands take the prefix di. Because the name triphenylphosphine already contains a numerical prefix (tri), two of them are shown by bis with the ligand in parentheses: bis(triphenylphosphine).

• Oxidation state of Ni: x + 2(−1) + 2(0) = 0, so x = +2, written as nickel(II). The complex is neutral, so the metal keeps its plain name.

Why the other options are incorrect

• Option (2) Nickel chlorido bis(triphenyl phosphine) — Incorrect. The metal must be named after the ligands, the two chlorido ligands need the prefix di, and the oxidation state (II) is missing.

• Option (3) Diphenyl phosphine Nickel (II) chloride — Incorrect. The ligand is triphenylphosphine (PPh₃), and the two chloride ions are ligands inside the coordination sphere, not a counter ion; the complex is neutral.

• Option (4) Dichlorobis (Diphenyl phosphine) Nickel (II) — Incorrect. The chloride ligand is named chlorido, and the phosphine ligand carries three phenyl groups (triphenylphosphine), not two.

NCERT (2026-27 edition):
Naming of Mononuclear Coordination Compounds – “… When the names of the ligands include a numerical prefix, then the terms, bis, tris, tetrakis are used, the ligand to which they refer being placed in parentheses. For example, [NiCl₂(PPh₃)₂] is named as dichloridobis(triphenylphosphine)nickel(II).”

Note: The same/similar question has been asked in different years by NTA as per the details given below: