Isolation and structure elucidation of 11-desacetoxywortmannin

The structure of 11-desacetoxy-wortmannin ( 3 ), a new antiinflammatory metabolite of the fungus Penicillium funiculosum THOM, has been elucidated by physico-chemical methods and chemical correlation with wortmannin ( 1 ).     

Calixarenes 11. Crystal and molecular structure ofp-tert-butylcalix[8]arene

Monoclinic prisms were obtained by slow evaporation of a pyridine solution ofp-tert-butylcalix[8]arene: space groupP2₁/c,a=20.312(3),b=23.020(2),c=20.006(6) ; =113.05(2)⁰;V=8707.6 ų;Z=4. Refinement led to anR value of 0.166 for 4231 reflections which, although high, is sufficient to establish the conformation of the molecule as a pleated loop in which the eight hydroxyl groups are arranged in a slightly undulating, almost planar, intramolecularly hydrogen bonded cyclic array. The possible inferences for the conformation ofp-tert-butylcalix[8]arene in solution are discussed. Supplementary Data relating to this article are deposited with the British Library as Supplementary Publication No. SUP 82019.     

SrZn11: a new binary compound with the BaCd11 structure

Single crystals of strontium undecazinc, SrZn₁₁, were obtained when decomposing SrZn₂ under conditions of high pressure and high temperature. The new binary Sr–Zn compound crystallizes in the space group I4₁/amd (BaCd₁₁ structure type) with one Sr position (m2) and three Zn sites (m2, .2/m., 1). The structure is described in terms of all‐face‐capped Zn₈ tetrahedra as the central building unit, defined by the Zn atoms on .2/m. and 1. The building units are condensed into chains by the central tetrahedra sharing edges, and the chains are interconnected by shared capping atoms. The resulting three‐dimensional framework of Zn atoms yields channels that are occupied by Sr and Zn atoms on the high‐symmetry m2 positions.     

The gas-phase structure of 1-selena-closo-dodecaborane(11), 1-SeB11H11, determined by the concerted use of electron diffraction and computational methods

The molecular structure of 1-selena-closo-dodecaborane(11), 1-SeB11H11, has been determined by the concerted use of quantum chemical calculations and gas-phase electron diffraction. The structure has C(5v) symmetry and is distorted from a regular icosahedron mainly through the expansion of the pentagon of boron atoms adjacent to selenium, with r(a3,1)(B-B) = 192.2(2) pm. The Se-B bond length is extremely well determined [r(a3,1) (Se-B) = 212.9(2) pm] and this is reflected by a pronounced peak in the radial-distribution curve. The accuracy of the experimental structure, as well as that calculated at the MP2/962(d) level, has been gauged by comparison of the 11B chemical shifts (calculated at two different gauge-including atomic orbitals (GIAO) levels) with experimental NMR values. The inclusion of electron correlation in the magnetic property calculations (GIAO-MP2) gave superior results to those carried out using GIAO-Hartree-Fock.     

Strained heterocyclic systems. 11. Crystal and molecular structure of 1,2-dihydrocyclobuta[b]quinoline

The structure of the title compound (1) has been elucidated by an X-ray crystal determination. The crystals are triclinic, space group PI with a unit cell of dimensions a = 6.6109(5), b = 7.5939(4), c = 9.3171(6), α = 77.133(5), β = 75.566(6), γ = 63.575(5). The model was refined to an R value (unweighted) of 4.3% for 1551 independent reflections. The distortion of the heterocyclic ring, with a CNC bond angle of 112.5,° is in accordance with a prior calculation and relates to the observed reduction in basicity.