CBSE Class 12 · 2006 · Delhi · Coordination CompoundsShort Answer

a) Using valence bond theory, predict the geometry and magnetic character of [Cr(NH

_{3}

)

_{6}

]

^{3 +}

. [Cr = 24]
b) Give one example of the application of coordination compounds in medicine.

Solution

(a) Cr

^{3 +}

= 3d

^{3}

: three unpaired electrons; two vacant 3d + 4s + three 4p → d

^{2}

^{3}

.
Geometry: octahedral.
Magnetic character: 3 unpaired electrons, paramagnetic (μ = √15 ≈ 3.87 BM).
(b) Medicine: \textit{cis}-platin, cis-[Pt(NH

_{3}

)

_{2}

_{2}

], is used in cancer chemotherapy (it binds DNA and stops tumour-cell division). (Also acceptable: EDTA chelation therapy for lead poisoning.)

CBSE Class 12 Board · 2006 · Delhi · Subjective