title: Molecular structure of hydrazoic acid with hydrogen-bonded tetramers in nearly planar layers.
abstract: Hydrazoic acid (HN(3))--potentially explosive, highly toxic, and very hygroscopic--is the simplest covalent azide and contains 97.7 wt % nitrogen. Although its molecular structure was established decades ago, its crystal structure has now been solved by X-ray diffraction for the first time. Molecules of HN(3) are connected to each other by hydrogen bonds in nearly planar layers parallel to (001) with stacking sequence A, B, ... The layer distance, at 2.950(1) Å, is shorter than that in 2H-graphite [3.355(2) Å]. The hydrogen bonds N-H···N are of great interest, since the azido group consists of three homonuclear atoms with identical electronegativity, but different formal charges. These hydrogen bonds are bifurcated into moderate ones with ≈2.0 Å and into weak ones with ≈2.6 Å. The moderate ones build up tetramers (HN(3))(4) in a nearly planar net of eight-membered rings. To the best of our knowledge, such a network of tetramers of a simple molecule is unique.
authors.affiliation: Department of Chemistry, Energetic Materials Research, Ludwig-Maximilian University of Munich, Butenandtstrasse 5-13(D), D-81377 Munich, Germany.
authors.forename: Jürgen
authors.initials: J
authors.lastname: Evers
authors.forename: Michael
authors.initials: M
authors.lastname: Göbel
authors.forename: Burkhard
authors.initials: B
authors.lastname: Krumm
authors.forename: Franz
authors.initials: F
authors.lastname: Martin
authors.forename: Sergey
authors.initials: S
authors.lastname: Medvedyev
authors.forename: Gilbert
authors.initials: G
authors.lastname: Oehlinger
authors.forename: Franz Xaver
authors.initials: FX
authors.lastname: Steemann
authors.forename: Ivan
authors.initials: I
authors.lastname: Troyan
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Klapötke
authors.forename: Mikhail I
authors.initials: MI
authors.lastname: Eremets