Give any two methods of preparation of diborane ?

1) Diborane is prepared by treating boran trifluoride with LiAlH₄ in dry ether.
$4{\mathrm{BF}}_3+3{\mathrm{LiAlH}}_4\stackrel{ }{\to }2{\mathrm{B}}_2{\mathrm{H}}_6+3\mathrm{LiF}+3{\mathrm{AlF}}_3$
2) It is prepared by the oxidation of sodium boro hydride with I₂
$2{\mathrm{NaBH}}_4+{\mathrm{I}}_2\stackrel{ }{\to }{\mathrm{B}}_2{\mathrm{H}}_6+2\mathrm{NaI}+{\mathrm{H}}_2$
3) Diborane produced on industrial scale by the reaction of BF₃ with sodium hydride
$2{\mathrm{BF}}_3+6\mathrm{NaH}\stackrel{450\mathrm{K}}{\to }{\mathrm{B}}_2{\mathrm{H}}_6+6\mathrm{NaF}$