Cover Picture (Angew. Chem. Int. Ed. Engl. 6/1990)

The cover illustration shows a ball and stick model of the methylsodium lattice. The sodium atoms are shown in red, the C atoms in gray. The structure contains tetrameric (in the middle and on the right and left sides of the picture) and monomeric NaCH 3 units. The ab‐initio elucidation of the structure of this still unknown alkali‐metal methanide has now been accomplished by combined neutron and synchroton‐radiation diffraction studies on NaCD 3 powders containing only small amounts of LiCD 3 . The structure of this real methylsodium —a LiCH 3 ‐stabilized form of which was known—is intermediate between the structure of methyllithium and that of methyl compounds of the heavy alkali metals. Further details of this impressive elucidation of the structure of a primary organometallic substance are reported by E. Weiss et al. on p. 650.