X-ray study of solid ammonia

Ammonia and deutero-ammonia have been studied by single-crystal and powder X-ray methods.There are four molecules in the cubic unit cell, and the space group is confirmed to be P2 1 3.The nitrogen parameter obtained by 0 least squares refinement is equal to 0.0401 for NH 3 at -102 C and the same for ND 3 at -l60C.Cell dimensions, determined by powder methods, are: a = 5.084 ~ for NH 3 at -l96C, 5.073 R for ND 3 at -l96C, 5.091 ~ for ND 3 at -l60C, and 5.138 R for NH 3 at -l02.C.Each ammonia molecule is involved in six hydrogen bonds of approximate length 3.4 ~.A possible assignment of the hydrogen atoms to these bonds is given.