The phenomenon of conglomerate crystallization of organic compounds. Part 4. The structures of 2,2′-biphenyldisulfide (I) and 2,2′-biphenyldisulfide monoxide (II)

A racemic solution of 2,2′-biphenyldisulfide ( I ), C₁₂H₈S₂, produces conglomerate crystals of ( I ) belonging in space group P3₂21 (no. 154) with lattice constants: a = 7.38 (3) Å, b = 7.38 (3), c = 16.20 (2) Å; V = 766.6 ų and d(calc; M.W. = 216.32, z = 3) = 1.406 g-cm⁻³, d(meas) = 1.47 g-cm⁻³. A total of 1150 data were collected over the range of 4° ≤ 2θ ≤ 60° using film data (Weissenberg); of these, 448 independent and with I ≥ 3σ(I)] were used in the structural analysis. Refinement converged to final residuals of 0.080 and 0.082 for R(F) and R_W(F), respectively. The molecule is located at the twofold axis of the space group. A solution of 2,2′-biphenyldisulfide mono-oxide ( II ), C₁₂H₈S₂O, produces centrosymmetric crystals of II belonging in space group P2₁/c with lattice constants: a = 9.947 (1) Å, b = 7.162 (2), c = 15.420 (3) Å, and β = 107.56 (1)°; V = 107.56 (1) ų and d(calc; M.W. = 232.31, Z = 4) = 1.473 g-cm⁻³. A total of 2114 data were collected over the range of 4° ≤ 2θ ≤ 50°; of these, 1089 independent and with I ≥ 2.5σ(I)] were used in the structural analysis. Data were corrected for absorption (μ = 4.539 cm⁻¹), and the relative transmission coefficients ranged from 0.9198 to 0.9998. Refinement converged to final residuals of 0.0313 and 0.0300 for R(F) and R_w(F), respectively. For I , the central six-membered ring C₄S₂ contains a helical C₂S₂ fragment whose conformational chirality is defined by a torsional angle of 59.98°. The benzene rings are the expected, planar hexagons characteristic of aryl rings. By comparison with I , the torsional angle of the C₂S₂ fragment of the mono-oxide is diminished (52.9°) by the introduction of the S=O fragment. We believe alteration of molecules (such as functionalization) causing large changes in torsional angles of helical fragments of molecules may play a role in the selection of their crystallization mode; however, it is not the only factor dictating that choice, which is also affected by steric hindrance to the formation of short intermolecular contacts leading, in the solid state, to the formation of homochiral, infinite helical strings, as we shall demonstrate in the text. This study clearly shows the influence of those contacts on the formation of the strings. © 1998 John Wiley & Sons, Inc. Heteroatom Chem 9:65–74, 1998