IIT-JEE 2009 · Paper 2 · Chemistry Q7

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ChemistryMultiple correct+4 / -1Question 7 of 57

In the reaction
$\ce{2X + B2H6 -> [BH2(X)2]+ [BH4]-}$
the amine(s) X is(are)

\ce{NH3}

\ce{CH3NH2}

\ce{(CH3)2NH}

\ce{(CH3)3N}

Answer and worked solution

Official answer: A, B, C

Unsymmetrical cleavage. Small amines ( $\ce{NH3}$ , $\ce{CH3NH2}$ , $\ce{(CH3)2NH}$ ) split diborane unsymmetrically:
$\ce{B2H6 + 2NH3 -> [BH2(NH3)2]+[BH4]-}.$

Bulky amines such as $\ce{(CH3)3N}$ cleave it symmetrically, giving the adduct $\ce{Me3N\cdot BH3}$ .

(A), (B), (C)

Topics:Boranes Group 13

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IIT-JEE 2009 · Paper 2, Chemistry question 7