CBSE Class 12 · 2003 · Delhi · Coordination CompoundsShort Answer

Using the valence bond approach, deduce the shape and magnetic character of [Co(NH

_{3}

)

_{6}

]

^{3 +}

. (Atomic number of Co = 27)

Answer: Octahedral, d²sp³ (inner orbital); diamagnetic — all d⁶ electrons paired.

Solution

^{3 +}

= 3d

^{6}

. NH

_{3}

, a strong-field ligand, forces pairing: t

_{2 g}^{6}

with two 3d orbitals vacated.
Hybridisation: d

^{2}

^{3}

→ octahedral, inner-orbital complex.
Magnetic character: zero unpaired electrons → diamagnetic.

CBSE Class 12 Board · 2003 · Delhi · Subjective