title: Oxygenation of zinc dialkyldithiocarbamate complexes: isolation, characterization, and reactivity of the stoichiometric oxygenates.
abstract: S-oxygenation of dithiocarbamate (DTC) complexes has been implicated in their function as industrial anti-oxidants, as well as in their use as pesticides and most recently in their cumulative toxicity, but little is known of the species generated. Several S-oxygenated derivatives of N,N-disubstituted DTCs have been synthesized, characterized by a variety of methods, and their structure and reactivity examined. Low-temperature reaction of bis(N,N-diethyldithiocarbamato)zinc(II), Zn(deDTC)2 1, with oxygenating reagents (hydrogen peroxide, m-chloroperbenzoic acid, urea hydrogen peroxide) yields mono-oxygenated DTC complexes (N,N-peroxydiethyldithiocarbamato)(N,N-diethyldithiocarbamato)zin(II), Zn(O-deDTC)(deDTC), 2 and bis(N,N-peroxydiethyldithiocarbamato)zinc(II), Zn(O-deDTC)2, 3. The tetraoxygenated derivative bis(N,N-diethylthiocarbamoylsulfinato)zinc(II), Zn(O(2)-deDTC)2, 4, was cleanly obtained by initial reaction of the DTC salts with stoichiometric oxidant prior to complexation with Zn(II). X-ray crystallographic analysis of 2, 3, and 4 show that the peroxydithiocarbamate ligands are S,O-bound. Similar derivatives were obtained from the homoleptic dimethyl and pyrollidine DTC Zn complexes. These oxygenated species display unique 1H and 13C NMR variable-temperature spectra, as the symmetry of DTC ligand is broken upon oxygenation; total line shape analysis (TLSA) was used to compare the energetic parameters for rotation about the C-N bond in several derivatives. Compounds 2, 3, and 4 were deoxygenated by alkyl phosphine, regenerating the parent dithiocarbamate 1. The peroxydithiocarbamate complexes were susceptible to base-catalyzed hydrolytic decomposition, giving ligand-based products indicative of S-oxidation and S-extrusion.
authors.affiliation: Department of Chemistry, University of California, Irvine, CA 92697-2025, USA.
authors.forename: Daniel F
authors.initials: DF
authors.lastname: Brayton
authors.forename: Kristine
authors.initials: K
authors.lastname: Tanabe
authors.forename: Mariya
authors.initials: M
authors.lastname: Khiterer
authors.forename: Kian
authors.initials: K
authors.lastname: Kolahi
authors.forename: Joseph
authors.initials: J
authors.lastname: Ziller
authors.forename: John
authors.initials: J
authors.lastname: Greaves
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Farmer
mesh_terms: D000975:Antioxidants / Q000737:chemistry; D002219:Carbamates / Q000737:chemistry; D002384:Catalysis; D006868:Hydrolysis; D008024:Ligands; D008956:Models, Chemical; D008958:Models, Molecular; D016877:Oxidants / Q000737:chemistry; D010100:Oxygen / Q000737:chemistry*; D010720:Phosphines / Q000737:chemistry; D011108:Polymers / Q000737:chemistry; D013053:Spectrophotometry; D013696:Temperature; D013859:Thiocarbamates / Q000737:chemistry*; D017967:Zinc Compounds / Q000737:chemistry*
chemical_list: D000975:Antioxidants; D002219:Carbamates; D008024:Ligands; D016877:Oxidants; D010720:Phosphines; D011108:Polymers; D013859:Thiocarbamates; D017967:Zinc Compounds; D010100:Oxygen