Molecular Geometry of Androsterone

Abstract

THE structure of androsterone, C₁₉H₃₀O₂ (Fig. 1), the first male sex hormone to be discovered, was determined recently by High¹ by vector coincidence methods. The space group of this compound is P2₁; the unit cell constants are a = 9.56 Å, b = 7.90 Å, c = 11.78 Å, = 111.36°, Z = 2, and the measured density equals 1.164 g cm⁻³. High's atomic positional parameters have been used to calculate the quantitative geometry of the androsterone molecule as follows. The final monoclinic fractional co-ordinates (x, y, z) were converted to Cartesian coordinates in Å (p, q, r) using the expressions p = a₀x + c₀z cos β, q = b₀y, and r = c₀z sin β, where a₀, b₀ and c₀ are taken in the Donnay setting (a₀ = 11.78 Å, b₀ = 7.90 Å, c₀ = 9.56 Å). The Cartesian Å co-ordinates were used, in turn, to compute a series of ‘best’ planes (Table 1) to which various geometrical features of the molecule could be referred, namely, the root mean square distances of atoms from the ‘best’ planes (Table 2), the perpendicular distance of individual atoms from the ‘best’ planes (Table 3), and the angles between the ‘best’ planes and various sub-portions thereof (Table 4). The ‘best’ plane calculations were performed on an IBM 1620 computer using the ‘best’ plane ‘Fortran’ programme of Harris and Harker².