Deduce the shape and magnetic behaviour of the complex ion [Co(NH$_3$)$_5$NO$_2$]$^{2+}$. [Atomic number of Co = 27]

CBSE Class 12 · 2001 · Delhi Compartment · Coordination CompoundsShort Answer

Deduce the shape and magnetic behaviour of the complex ion [Co(NH

_{3}

)

_{5}

_{2}

]

^{2 +}

. [Atomic number of Co = 27]

Answer: Octahedral, d²sp³; diamagnetic (Co³⁺ d⁶ fully paired by the strong-field ligands).

Co oxidation state: x + 0 + (−1) = +2 ⇒ Co

^{3 +}

= 3d

^{6}

.
NH

_{3}

/NO

_{2}^{-}

are strong-field ligands: the six d electrons pair into three 3d orbitals (t

_{2 g}^{6}

), leaving two empty 3d orbitals for d

^{2}

^{3}

hybridisation.
Shape: octahedral.
Magnetic behaviour: no unpaired electron → diamagnetic.

CBSE Class 12 Board · 2001 · Delhi Compartment · Subjective