CRYSTAL AND MOLECULAR-STRUCTURE OF ASEBOTOXIN-IV

The three-dimensional structure of asebotoxin IV has been determined b y X-ray diffraction at room temperature. The crystals are triclinic, s pace group Pl, with a=9.934(2), b=8.8746(9), c=7.0073(9) angstrom, alp ha=71.05(l), beta=80.04(1), gamma=70.71(l)-degrees, V=549.8(2) angstro m3, z=i. D(c)=1.337 g cm-3. The structure was solved by the direct met hod and refined by the full matrix least-squares method to a final R=0 .038 for 1604 independent reflections with F(o) > 3sigma (F(o)). The m olecule is based on a tetracyclic structure consisting of two five-mem bered, one six-membered and one seven-membered rings with various conf ormations.