The Form of the Carbon Atom in Crystal Structure

Abstract

A. GERSTÄCKER, H. Möller, and A. Reis have published an account of the crystal structure of pentaerythritol tetra-acetate (Zeitsch. f. Kryst., 66, 355; Jan. 1928), in which they assign the crystals to the space-group C³_4h with a simple tetragonal lattice (Γ_t). There are two molecules of pentaerythritol tetraacetate to the unit cell and the space-group C³_4h with a Γ_t lattice requires eight asymmetric molecules per unit cell. Therefore the molecules of pentaerythritol tetra-acetate must have some kind of fourfold symmetry. There are two types of fourfold symmetry possible in this space-group—either a simple fourfold rotation axis or a fourfold alternating axis. Messrs. Gerstäcker, Möller, and Reis have chosen the former, since it leads to a molecule which can be built into a chain-like structure, and the latter does not.