Crystal and molecular structure of 4-isopropyltropolone (β-thujaplicin)

Abstract

The π-electron system in 4-isopropyltropolone (IV) has been shown by X-ray crystallographic analysis, by use of three-dimensional counter data, to be partially delocalised. Within the ring, the C(1)–C(2) bond remains essentially a single bond (1·469 Å), and the means of the other formal single and double C–C bonds are 1·416 and 1·362 Å. The atoms of the ring deviate slightly, but significantly, from coplanarity. The crystals are monoclinic, space group I2/c with Z= 8 in a cell of dimensions: a= 17·063, b= 6·469, c= 15·970 Å, and β= 90·77°. The structure was solved by the symbolic addition procedure and refined by least squares methods to a final R of 8·3% for 1272 structure amplitudes.