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Question
What do you understand by electron-deficient? Provide justification with a suitable example.
Solution
Molecular hydrides are classified on the basis of the presence of the total number of electrons and bonds in their Lewis structures as:
Electron-deficient hydrides:
An electron-deficient hydride has very few electrons, less than that required for representing its conventional Lewis structure e.g. diborane (B2H6). In B2H6, there are six bonds in all, out of which only four bonds are regular two centered-two electron bonds. The remaining two bonds are three centered-two electron bonds i.e., two electrons are shared by three atoms. Hence, its conventional Lewis structure cannot be drawn.
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