The crystal structures of an inorganic butane analogue,
NH3BH2NH2BH3 (DDAB), were determined using single crystal
X-ray diffraction, revealing both anti and gauche conformations.
The anti conformation is stabilized by intermolecular dihydrogen
bonds in the crystal whereas two gauche conformations of DDAB
observed in its 18-crown-6 adducts are stabilized by an intramolecular
dihydrogen bond. The two gauche conformations show
rotational isomerization but whether they are a pair of enantiomers
is yet to be defined.