The number of 2-centre-2-electron and 3-centre-2-electron bonds in B₂H₆, respectively, are :

In diborane each B atom undergoes sp³  hybridisation ,it contains two B-H-B bridges . Each bridge bond is formed by overlapping of one "B"sp³  hybrid orbital with one electron, hydrogen s-orbital with one electron and another boron sp³ hybrid orbital without electron .That is the bridge head bond is a electron deficient three centre two electron bond.

The number of atoms involved in bridged bonds in one diborane molecule is four.