Coordination compounds

The complex [Co(en)3]3+ is octahedral and lacks any plane or center of symmetry, allowing it to exist as a pair of non-superimposable mirror images, which means there are 2 optical isomers. Option D is incorrect because the chelated rings create a chiral propeller-like structure, preventing it from being optically inactive.

Strong field cyanide ligands force the pairing of 3d electrons in the nickel(II) ion, leaving one d-orbital vacant for dsp2 hybridization. Distractor A is incorrect because sp3 hybridization occurs with weak-field ligands like chloride, which do not force electron pairing and result in a tetrahedral geometry.

Bidentate ligands are molecules or ions that have two donor atoms capable of coordinating to a central metal ion simultaneously. A diagram for this topic isn't available yet — the worked example below walks the same reasoning step by step.

• !Monodentate ligands are incorrect because they only possess a single donor atom and can form only one coordinate bond.
• !Distractor A is incorrect because sp3 hybridization occurs with weak-field ligands like chloride, which do not force electron pairing and result in a tetrahedral geometry.
• !Option D is incorrect because the chelated rings create a chiral propeller-like structure, preventing it from being optically inactive.

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