Question

The magnetic moment of $\left[ Mn ( CN )_{6}\right]^{3-}$ is $2.8 BM$ and that of $\left[ MnBr _{4}\right]^{2-}$ is $5.9 BM$ The hybridization and geometries of these complex ions

• A. $s p^{3} d^{2}$ octahedral and dsp $^{2}$ tetrahedral
• B. $d^{2} s p^{3}$ octahedral and $d s p^{2}$ square plannar
• C. $d^{2} s p^{3}$ octahedral and $s p^{3}$ tetrahedral
• D. $sp ^{3} d ^{2}$ octahedral and $sp ^{3}$ square plannar

Answer 1

Answer: (C)

$\left[ Mn ( CN )_{6}\right]^{3-}: M n^{3+}=3 d ^{4} 4 s ^{\circ}= t _{2g}^{2,1,1} eg ^{\circ \circ}= d ^{2} sp ^{3}$ hybridised
no. of unpaired electrons $=2$
magnetic moment $=\mu_{ B }=\sqrt{2 \times 4} BM \simeq 2.8 BM$
$\left[ MnBr _{4}\right]^{2-}: M n^{2+}=3 d ^{5} 4 s ^{\circ}= eg ^{1,1} t _{2g}^{1,1,1}= sp ^{3}$ hybridised
no. of unpaired electrons $=5$
magnetic moment $=\mu_{ B }=\sqrt{5 \times 7} BM \simeq 5.9 BM$