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.

Mixed crystal of bis(μ2‐N,N‐di‐n‐butyldithiocarbamato‐S,S,S′)‐bis(N,N‐di‐n‐butyldithiocarbamato‐S,S′)‐di‐zinc(II) and bis(μ2‐N,N‐di‐n‐butyldithiopercarbamato‐S,O,O′)‐bis(N,N‐di‐n‐butyldithiocarbamato‐S,S′)‐di‐zinc(II)

“…The preparation of zinc dithiopercarbamates by oxidation of sodium dithiocarbamates [12,13] and by direct oxidation of zinc dithiocarbamates [14] yields mixtures of 1, 2 and higher oxidized compounds such as zinc thiocarbamoylsulfinates [7,12,14,15] (Scheme 1) and the purification of the oxygenated species proves to be difficult.…”

“…X-ray crystal structure analysis Crystal data were collected at 293(2) K on an Enraf-Nonius CAD-4 diffractometer for a crystal of dimensions 0. 20 (3) 9447 (1) 252 (1) 3004 (1) 94(1) S (4) 10794 (6) 5143 (7) -658(9) -943(15) 560(30) C (7) 7364 ( (11) 10328 (4) 1407 (4) 4706 (5) 145(3) C (12) 10523 (4) 2018 (4) 4248 (7) 178(4) C (13) 10154 (5) 2789 (5) 4106 (9) 236(6) C (14) 10493 (7) 3428 (6) 3958 (15) 404(14) C (15) 11378 (3) 493 (6) 5801 (4) 160(4) C (16) 11986 (2) 708 (5) 5762 (5) 125(3) C (17) 12712 (3) 449 (6) 6741 (5) 160(4) C (18) 13312 (4) 691 (8) …”

Complexation of the Vulcanization Accelerator Tetramethylthiuram Disulfide and Related Molecules with Zinc Compounds Including Zinc Oxide Clusters (Zn4O4)

“…[21] The S,O-bound ligand R 2 NCS 2 O À is also present in the dinuclear zinc complexes [{ZnA C H T U N G T R E N N U N G (OS 2 CNBu 2 ) 2 } 2 ] [22] and [{ZnA C H T U N G T R E N N U N G (OS 2 CNEt 2 ) 2 } 2 ]. [23] However, in the last three compounds the ligands are anions, not radicals as in 12 a.…”

A novel heterocyclic atom exchange reaction with Lawesson's reagent: a one-pot synthesis of dithiomaltol

“…7 Several groups have been investigating the modulation of these activities by replacing the oxy-functionalities with sulfur. [8][9][10][11][12][13] The simplest analogue, thiomaltol, or 3-hydroxy-2-methyl-4-thiopyrone (Htma), was first synthesized in 1969 14 and used for the extraction and determination of a variety of cationic metals. [15][16][17][18][19] Most recently, thiomaltol and related ligands have been reinvestigated for their biological activity, as metalloprotein protease inhibitors and as pro-oxidant cancer drugs.…”

“…[15][16][17][18][19] Most recently, thiomaltol and related ligands have been reinvestigated for their biological activity, as metalloprotein protease inhibitors and as pro-oxidant cancer drugs. 8,12,13,[20][21][22][23] Thiomaltol and related species may be obtained directly from the parent a-hydroxy ketone by reaction with thionating agents like P 4 S 10 or Lawesson's reagent (LR). In one such reaction with excess LR, we observed a product resulting from an apparent second substitution of sulfur for oxygen in maltol by LR, route A in Scheme 2.…”