Electron Deficient Compounds. VI. The Structure of Beryllium Chloride

The simple compound, beryllium chloride, offers an opportunity to study halogen bridge bonding. Beryllium chloride is isomorphous with dimethylberyllium and silicon disulfide. The orthorhombic unit, a0=9.86, b0=5.36, c0=5.26A contains four beryllium chloride molecules. The structure consists of continuous chains:[Complex chemical formula]with an essentially tetrahedral configuration about beryllium. The Cl–Be–Cl bond angle within the four membered rings is 98.2° which is less than the tetrahedral angle, as is found in SiS2, instead of more, as in dimethylberyllium. The bond angles indicate that all bonds in beryllium chloride contain an electron pair, so that chlorine uses an unshared pair in forming bridge bonds. Hence, chlorides isomorphous with electron deficient metal alkyls are not to be classified as electron deficient compounds.