Consider the octahedral complex [Ni(tren)BrCl]²⁺, where tren has a formula of N(CH₂CH₂NH₂)₃ and can be simplified as:
.
(a)The tren is tetradentate. Define tetradentate and explain how tren is considered to be tetradentate.
(b)Sketch all possible stereoisomers of [Ni(tren)BrCl]²⁺ and classify each stereoisomer as either chiral or achiral.

• A. Tetradentate means that there are 4 donor atoms in the ligand. Tren is tetradentate because of its 4 N atoms which act as donor atoms.
• B. Tetradentate means that there are 3 donor atoms in the ligand. Tren is tetradentate because of its 3 N atoms which act as donor atoms.
• C. Tetradentate means that there are 3 donor atoms in the ligand. Tren is tetradentate because of its 3 N atoms which act as donor atoms.
• D. Tetradentate means that there are 4 donor atoms in the ligand. Tren is tetradentate because of its 4 N atoms which act as donor atoms.

Answer: (A)