CBSE Class 12 · 2007 · All India · Coordination CompoundsShort Answer

Describe, for any two of the following complex ions, the type of hybridisation, shape and magnetic property:
i) [Fe(H

_{2}

_{6}

]

^{2 +}

ii) [Co(NH

_{3}

)

_{6}

]

^{3 +}

iii) [NiCl

_{4}

]

^{2 -}

(Atomic numbers: Fe = 26, Co = 27, Ni = 28)

Solution

(i) [Fe(H

_{2}

_{6}

]

^{2 +}

: Fe

^{2 +}

= 3d

^{6}

; H

_{2}

O is weak-field (no pairing) → outer-orbital \textbf{sp

^{3}

^{2}

}, octahedral, 4 unpaired electrons — paramagnetic (μ ≈ 4.90 BM).
(ii) [Co(NH

_{3}

)

_{6}

]

^{3 +}

: Co

^{3 +}

= 3d

^{6}

; NH

_{3}

is strong-field (pairing) → inner-orbital \textbf{d

^{2}

^{3}

}, octahedral, 0 unpaired — diamagnetic.
(iii) [NiCl

_{4}

]

^{2 -}

: Ni

^{2 +}

= 3d

^{8}

; Cl

^{-}

weak-field → \textbf{sp

^{3}

}, tetrahedral, 2 unpaired — paramagnetic (μ ≈ 2.82 BM).
(Any two of the three earn full marks.)

CBSE Class 12 Board · 2007 · All India · Subjective