The X-Ray Structures of Sulfoxides

We have structurally characterized and investigated a range of sulfoxide compounds containing aryl and alkyl substituents. Compounds 1 and 3-6 all crystallize in an orthorhombic space group, where compounds 2 and 7 crystallize in a monoclinic space group. The unit cell parameters of the compounds are as follows: 1 (Fdd2), a = 17.653(5) angstrom, b = 53.153(14) angstrom, and c = 10.071(3) angstrom; 2 (P2(1)/c), a = 7.894(13) angstrom, b = 5.653(10) angstrom, and c = 27.02(5) angstrom, beta = 97.347(15)degrees; 3(P2(1)2(1)2(1)), a = 5.7569(6) angstrom, b = 12.2139(12) angstrom, and c = 17.5974(18) angstrom; 4 (Pca2(1)), a = 8.256(4) angstrom, b = 5.470(3) angstrom, and c = 23.995(13) angstrom; 5 (P212121), a = 5.848(4) angstrom, b = 7.568(5) angstrom, and c = 27.650(17) angstrom; 6 (Pbca), a = 10.0569(15) angstrom, b = 9.9403(16) angstrom, and c = 17.843(3) angstrom; and 7 (Pc), a = 13.217(4) angstrom, b = 5.3766(14) angstrom, and c = 8.370(2) angstrom, beta = 90.673(6)degrees. The S=O bond distances in these compounds range from 1.489(7) to 1.515(8) angstrom. In all seven structures, the O(1)-S-C bond angles vary from 105.1(4) to 111.7(30)degrees and the C(1)-S(1)-C(11) bond angles range from 94.1(4) to 100.56(12)degrees. The compounds contain unique intra- and intermolecular interactions depending on the groups attached to the sulfoxide moiety. The polarity of the sulfoxide bond in these compounds allows for intramolecular S center dot center dot center dot O interactions to occur. When the sulfur is bound to alkyl groups, there tends to be a shorter S center dot center dot center dot O intermolecular distance than when the sulfur is bound to aromatic substituents. Additionally, if the sulfur is flanked by an aryl group, the S-C bond distance is slightly shorter than if flanked by an alkyl group, suggesting a possible weak O center dot center dot center dot H-ary1 intramolecular interaction, weak conjugation of the aromatic ring with the S-O bond or both. Furthermore, if the sulfur is flanked by an alkyl group, a CH2 proton of S-CH2-R can be properly oriented to participate in an intermolecular hydrogen bond with the sulfoxide oxygen of another molecule.