title: Three trithiadiazepines and a trithiatriazepine.
abstract: The structures of 6-nitro-1,3λ(4)δ(2),5,2,4-trithiadiazepine [C2HN3O2S3, (1)], 6,7-dinitro-1,3λ(4)δ(2),5,2,4-trithiadiazepine [C2N4O4S3, (2)], 1,3λ(4)δ(2),5,2,4-trithiadiazepine-6,7-dicarbonitrile [C4N4S3, (3)] and 7-acetyl-1,3λ(4)δ(2),5,2,4,6-trithiatriazepine [C3H3N3OS3, (4)] presented here include the most precise determinations of these seven-membered 10 π-electron aromatic ring systems published to date. Both (2) and (3) are sited around crystallographic twofold axes with half a molecule per asymmetric unit. Comparison with other published derivatives of these rings reveals the effect of substituents on bonding, conformations and intermolecular interactions, including π-stacking. The deformation density analysis of (2) is consistent with the expected bonding electron density from other theoretical and experimental studies.
authors.affiliation: Fox Technical Consulting, 602-1049 Chilco Street, Vancouver, BC, Canada V6G 2R7.
authors.forename: Ray
authors.initials: R
authors.lastname: Jones
keywords: bonding; crystal structure; deformation density; packing; trithiadiazepine; trithiatriazepine