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Question: Write the correct IUPAC name of the given complex $[NiBr_2(PPh_3)_2]$...

Write the correct IUPAC name of the given complex [NiBr2(PPh3)2][NiBr_2(PPh_3)_2]

A

Dibromido tris triphenylphosphine nickel (II)

B

Dibromido bis triphenylphosphine nickel (IV)

C

Dibromido bis triphenylphosphine nickel (II)

D

Dibromido bis triphenylphosphine nickelate (II)

Answer

Dibromido bis triphenylphosphine nickel (II)

Explanation

Solution

The IUPAC naming of coordination compounds follows specific rules:

  1. Identify the ligands and central metal atom:

    • Central metal atom: Nickel (Ni)
    • Ligands: Bromide (Br) and Triphenylphosphine (PPh₃)

  2. Determine the number of each ligand and their names:

    • There are two Bromide (Br) ligands. As an anionic ligand, its name becomes "bromido". Since there are two, it's "dibromido".
    • There are two Triphenylphosphine (PPh₃) ligands. Triphenylphosphine is a neutral ligand and its name is complex. For two such ligands, the prefix "bis-" is used, so "bis(triphenylphosphine)".

  3. Order the ligands alphabetically:

    • "Bromido" starts with 'b' and "Triphenylphosphine" starts with 't'. So, "dibromido" comes before "bis(triphenylphosphine)".

  4. Determine the oxidation state of the central metal atom:

    • Let the oxidation state of Ni be 'x'.
    • Each bromide ion (Br⁻) has a charge of -1.
    • Triphenylphosphine (PPh₃) is a neutral ligand, so its charge is 0.
    • The complex [NiBr2(PPh3)2][NiBr_2(PPh_3)_2] is neutral, so the sum of charges is 0.
    • x + 2(-1) + 2(0) = 0
    • x - 2 = 0
    • x = +2
    • So, the oxidation state of Nickel is (II).

  5. Name the central metal atom:

    • Since the complex is neutral, the metal name is simply "nickel". If it were an anionic complex, it would end in "-ate" (e.g., "nickelate").

  6. Assemble the name: Combining all parts in the correct order: Dibromido bis(triphenylphosphine)nickel(II)

Comparing this with the given options: (1) Dibromido tris triphenylphosphine nickel (II) - Incorrect prefix "tris". (2) Dibromido bis triphenylphosphine nickel (IV) - Incorrect oxidation state (IV instead of II). (3) Dibromido bis triphenylphosphine nickel (II) - Matches the derived name (parentheses around triphenylphosphine are often omitted in multiple-choice options for simplicity if the meaning is clear). (4) Dibromido bis triphenylphosphine nickelate (II) - Incorrect metal name "nickelate" (should be "nickel" for a neutral complex).

The most accurate IUPAC name is Dibromido bis(triphenylphosphine)nickel(II). Option (3) is the closest and correct choice among the given options.