(N(2))(6)Ne(7): A high pressure van der Waals insertion compound.

The binary phase diagram of N(2)-Ne mixtures has been measured at 296 K by visual observation and Raman spectroscopy. The topology of the phase diagram points to the existence of the stoichiometric compound N(2))(6)Ne(7). Its structure has been solved by single-crystal synchrotron x-ray diffraction. The N(2) molecules form a guest lattice that hosts the Ne atoms. This insertion compound can be viewed as a clathrate with the centers of the N(2) molecules forming distorted dodecahedron cages, each enclosing 14 Ne atoms. Remarkably, the N(2))(6)Ne(7) compound is somehow the first clathrate organized by the quadrupolar interaction.