title: X-ray investigations of sulfur-containing fungicides. II. Intramolecular forces governing the conformation of four novel alpha-phenylazo- and alpha-phenylhydrazono-beta-ketosulfones.
abstract: The crystal and molecular structures of four novel beta-ketosulfones, phenyl benzoyl(phenylhydrazono)methyl sulfone (I), phenyl benzoyl(4-nitrophenylhydrazono)methyl sulfone (II), (benzoyl)(phenyl)(phenylazo)methyl phenyl sulfone (III) and (benzoyl)(phenyl)(3-chlorophenylazo)methyl 4-tolyl sulfone (IV), have been investigated using X-ray analysis and density functional theory supplemented by ab initio Hartree-Fock calculations. The conformations of (I) and (II) are stabilized by strong intramolecular resonance-assisted hydrogen bonds formed between the sulfonyl and the alpha-hydrazono moieties. The following increase of a positive charge on the S atoms is compensated via pi-conjugation and stereoelectronic back-donation from the nearby beta-carbonyl group. Compounds (III) and (IV) adopt a strongly distorted propeller shape with pivotal tetrahedral C1 atoms. Distortion mostly follows from the approximate coplanarity of the alpha-azophenyl and alpha-phenyl moieties opposite each other. The main stereoelectronic interactions involve the donation of electron density from the alpha-azo N2 towards the sulfonyl S and the beta-carbonyl C2 atoms.
authors.affiliation: Institute of General and Ecological Chemistry (I-17), Technical University of Lódz, Zwirki 36, 90-924 Lódz, Poland. wmwolf@p.lodz.pl
authors.forename: W M
authors.initials: WM
authors.lastname: Wolf
mesh_terms: D018360:Crystallography, X-Ray; D005659:Fungicides, Industrial / Q000737:chemistry*; D006860:Hydrogen Bonding; D015394:Molecular Structure; D013450:Sulfones / Q000737:chemistry*
chemical_list: D005659:Fungicides, Industrial; D013450:Sulfones