Some statements about the structure of diborane are given below
A) Studies have confirmed that four hydrogens of diborane are one type and remaining two are of another type
B) Diborane contains two coplanar BH₂ groups
C) Diborane is a planar molecule
D) Boron of diborane undergoes sp² hybridization
The correct statements above are

C2H6	B2H6
2 x 4 = 8	2 x 3 = 6
6 x1 = 6	6 x 1 = 6
Total valency electrons = 14	Total valency electrons = 12

Diborane do not possess the ethane like structure, because in ethane formation 14 electrons are involved where as indiborane formation only 12 valency electrons are involved.Hence the diborane structure not similar to that of ethane.

Experimental evidences for diborane structure

I) From specific heat data values we can conclude that in between the two boron atoms free rotation is not possible.

II) From electron diffraction studies in diborane two BH₂ groups are present in one plane and bridged hydrogen atoms are perpendicular to the BH₂ plane.

 

                                                      

III) From NMR and Raman  spectral analysis data in diborane two types of hydrogen atoms are present.

a) Four terminal hydrogen atoms

b) Two bridged hydrogen atoms.

IV) Diborane on methylation gives tetramethylated diborane ,the bridged hydrogen atoms do not involve in methylation.

V) From bond-length data in diborane in diborane two types of B — H bond lengths are present .

a) Terminal B — H bond length1.19A⁰

b) Bridged B — H bond length is 1.34A⁰