Sultam and Sultim Structures, Part 3. Strong and Weak Hydrogen Bonds in 3-Oxosultams, 3-Oxosultims and 3-Alkoxysultams

Abstract

In order to study hydrogen bonding networks in cyclic sulfin- and sulfonamides, X-ray structures were determined for 3-oxosultams 3a, c - e, 3-alkoxysultams 5b, f and 3-oxosultim 2f, all of which show predominantly weak intermolecular hydrogen bonds. The 3-oxosultam 3a forms tetrameric units by combining two symmetry-independent molecules through weak aromatic C-H· · ·O-S-O hydrogen bonds without participation of the carbonyl groups. The 3-oxosultam 3c, with two chloro substituents in the N-aryl ring show a polymer arrangement of the molecules through intermolecular association of the SO2 and CO groups also with the aromatic H-atoms of the aryl rings. Sultam 3d shows the first polymer chain in the 3-oxosultam series by the strong O-H· · ·O=C hydrogen bonds without participation of the SO2 group. Two new ‘head-to-head’ dimers with a 10-membered ring are found for 3-alkoxysultams 5b, 5f through weak C-H· · ·O-S-O hydrogen bonds. In the 3-oxosultim 2f weak intermolecular hydrogen bonds are observed to form a two-dimensional network with the two methylene groups, the carbonyl function and the chloro atom but, surprisingly, without the strong S-oxide acceptor group.