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Hydrogen

Question
CBSEENCH11006906

What characteristics do you expect from an electron-deficient hydride with respect to its structure and chemical reactivity ? 

Solution
Since electron deficient hydrides have lesser electrons to form normal covalent bonds, therefore we expect the following characteristics from these hydrides:
(i) They generally exist in polymeric forms such as B2H6, B4H10.(AlH3)n etc.
(ii) They react with many metals, non-metals and their compounds. Hence these hydrides are very reactive. 
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2 NaH left parenthesis straight s right parenthesis space plus space straight B subscript 2 straight H subscript 6 left parenthesis straight g right parenthesis space space rightwards arrow with Diethyl space ether on top space stack 2 Na to the power of plus space open square brackets BH subscript 4 close square brackets to the power of minus space left parenthesis straight s right parenthesis with Sodium space borohydride below
(iii) They act as Lewis acids and thus form complexes with Lewis bases.
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stack straight B subscript 2 straight H subscript 6 with Diborane below space plus space stack 2 NMe subscript 3 with Trimethylamine below space rightwards arrow space space space 2 straight H subscript 3 straight B space space leftwards arrow space space space NMe subscript 3