Publications [#233604] of Andrew T. McPhail

Journal Articles

  1. Coggon, P; McPhail, AT; Sim, GA, "Sesquiterpenoids. Part X. Stereochemistry of Pregeijerene: Crystal Structure of the Pregeijerene-Silver Nitrate Adduct", J. Chem. Soc. B, 1970, 1024-1028, Royal Society of Chemistry (RSC) [doi].
    (last updated on 2026/01/21)

    Abstract:
    Crystal-structure analysis of C12H18,AgNO3,H2O, the silver nitrate adduct of pregeijerene, has shown the tri-substituted double bonds of the 1,5-dimethylcyclodeca-1,5,7-triene to be trans and the disubstituted double bond cis. The silver ion is co-ordinated to the C(5)-C(6) double bond of one molecule and the C(7)-C(8) double bond of a related molecule, with Ag-C distances 2.42-2.47 Å. The olefin adopts a conformation in which the methyl groups are on the same side of the mean plane of the ring. The transannular separation C(2) ⋯ C(6), 2.91 Å, is notably short. The C(6)-C(7)-C(8)-C(9) torsion angle is 1.5°; the C(10)-C(1)-C(2)-C(3) and C(4)-C(5)-C(6)-C(7) torsion angles are 165.4 and 150.4°. The deviation from planar trigonal bonding at C(1) is small, but the apparent twist of 29.6° in the complexed trans double bond C(5)-C(6) involves a component of 19.5° arising from out-of-plane displacement of the carbon-carbon bonds at C(5). The adduct crystallizes in the monoclinic space group P21/C. with Z = 4 in a cell of dimensions a = 10.19, b = 9.17, c = 14.80 Å, β = 100.8°. The structure was determined by Fourier and least-squares methods and refined to R 0.105.