Ca4As3 - a new binary calcium arsenide.

The crystal structure of the binary compound tetra-calcium triarsenide, Ca4As3, was investigated by single-crystal X-ray diffraction. Ca4As3 crystallizes in the Ba4P3 structure type and is thus a homologue of isotypic Sr4As3. The unit cell contains 32 Ca(2+) cations, 16 As(3-) isolated anions and four centrosymmetric [As2](4-) dumbbells. The As atoms in each of the dumbbells are connected by a single bond, thus this calcium arsenide is a Zintl phase.