High-Pressure Structural Studies of CL-20

Abstract

2,4,6,8,10,12-hexanitrohexaazaisowurtzitane (HNIW, more commonly known as CL-20 after the China Lake Research Facility, USA) was first synthesised in the late 1980s although the detailed synthetic procedure was only published in 1998. CL-20 is a polycyclic nitramine with six nitro groups bonded to an isowurtzitane cage. The low ratio of carbon atoms to nitramine moieties, combined with the inherent strain in the isowurtzitane cage and the increased density (with respect to its monocyclic analogue) have led to CL-20 being characterised as ``the densest and most energetic explosive known.'' It is not surprising therefore that a significant amount of research has been aimed at assessing its explosive performance, sensitivity and thermal properties. Furthermore spectroscopic and diffraction techniques have been used to explore the rich polymorphism of CL-20.