Substituierte Heptaarsane(3) As7(Mme3)3 (M = Si, Ge, Sn) mit Nortricyclenstruktur / Substituted Heptaarsanes(3) As7(Mme3)3 (M = Si, Ge, Sn) with Nortricyelene Structure

Abstract

The heptaarsanes(3) As7(Mme3)3 (M = Si, Ge, Sn) with nortricyclene structure have been synthesized by heterogeneous and homogeneous reactions from K3As7 and Rb3As7, respectively, with Mme3Cl. The crystal structures have been determined. The compounds are isotypic and crystallize in unit cells of R3̄̄ symmetry, containing pairs of enantiomers. The bond lengths d(As-As) in the nortricyclene skeleton are nearly uneffected by the substituents and show the sequence typical for covalent nortricyclenes: d(basal) = 244.3 pm > d(basal-equatorial) = 242.7 pm > d(equatorial-apical) = 240.7 pm (mean values). The spread-off of the Mme, substituents decreases as going from P7 to As7 skeletons as well as with increasing size of M