Write any two methods of preparation of diborane. How does it react with (i)Carbon monoxide and (ii)Ammonia ?

Explanation

Preparation of diborane:
`to` In industries diborane is prepared by the reaction between boron tri fluoride and lithium hydride.
`2BF_3 + 6LiH overset(450K)to B_2 H_6 + 6LiF`
Boron trichloride and hydrogen mixture subjected to silent electric discharge at low pressure to from diborane.
`2BCl_3 + 6H_2 to B_2 H_6 + 6HCl`
Boron trichloride undergo reduction with `LiAlH_4` to form diborane.
`3LiA//H_4 + 4BCl_3 overset("Ether")to 2B_2 H_6 + 3AlCl_3 + 3LiCl`
(a) Reaction with carbon monoxide :
Diborane reacts with CO at `100^@` C and 20 atm. pressure to form borane carbonyl.
`B_2 H_6 + 2CO underset("20 atm")overset(100^@ C)to 2BH_3 CO`
(b) Reaction with ammonia :
Diborane reacts with ammonia at `120^@` C first forms `B_2 H_6 2NH_3` (or) `[BH_2 (NH_3)_2 ]^+ [BH_4]^-` and on further heating forms borazole (or) borazine. Which is also called as "In organic benzene". It has iso structural with benzene. Hence it is named as "Inorganic Benzene",
`3B_2 H_6 + 6NH_3 overset(120^@C)to 3[BH_2(NH_3)_2 ]^+ [BH_4]^(-) overset(Delta)to underset("Borazole (or) Borazine")(2B_2N_3 H_6+ 12 H_2)`