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 co nglomerate crystals of (I) belonging in space group P3(2)21 (no. 154) with lattice constants: a = 7.38 (3) Angstrom, b = 7.38 (3), c = 16.20 (2) Angstrom, V = 766.6 Angstrom(3) 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 degrees less than or equal to 2 theta le ss than or equal to 60 degrees using film data (Weissenberg); of these , 448 [independent and with I greater than or equal to 3 sigma(I)] wer e used in the structural analysis. Refinement converged to final resid uals of 0.080 and 0.082 for R(F) and R-w(F), respectively. The molecul e is located at the twofold axis of the space group. A solution of 2,2 '-biphenyldisulfide mono-oxide (II), C12H8S2O, produces centrosymmetri c crystals of II belonging in space group P2(1)/c with lattice constan ts: a = 9.947 (1) Angstrom, b = 7.162 (2), c = 15.420 (3) Angstrom, an d beta = 107.56 (1)degrees; V = 107.56 (1) Angstrom(3) and d(calc; M.W . = 232.31, Z = 4) = 1.473 g-cm(-3). A total of 2114 data were collect ed over the range of 4 degrees less than or equal to 2 theta less than or equal to 50 degrees; of these, 1089 [independent and with I greate r than or equal to 2.5 sigma(I)] were used in the structural analysis. Data were corrected for absorption (mu = 4.539 cm(-1)), and the relat ive 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 h elical C2S2 fragment whose conformational chirality is defined by a to rsional angle of 59.98 degrees. The benzene rings are the expected, pl anar hexagons characteristic of aryl rings. By comparison with I, the torsional angle of the C2S2 fragment of the mono-oxide is diminished ( 52.9 degrees) by the introduction of the S = O fragment. We believe al teration of molecules (such as functionalization) causing large change s in torsional angles of helical fragments of molecules may play a rol e in the selection of their crystallization mode; however, it is not t he 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 s trings, as we shall demonstrate in the text. This study clearly shows the influence of those contacts on the formation of the strings. (C) 1 998 John Wiley & Sons, Inc.