Multiple Pathways for the Oxygenation of a Ruthenium(II) Dithiocarbamate Complex:  S-Oxygenation and S-Extrusion

Abstract

The reactions of Ru(bpy)(2)(N,N-dimethyldithiocarbamate)(+), 1, with O-atom-transfer reagents such as hydrogen peroxide, m-chloroperoxybenzoic acid, and oxone have been studied and several resulting derivatives isolated and structurally characterized. Both S-oxygenation and S-extrusion may occur depending upon reagent and conditions. Excess peroxygenation leads to a stable dioxygenate, Ru(bpy)(2)(N,N-dimethylthiocarbamatesulfinate-S,S)(+), 3. Stoichiometric oxygenation leads to mixtures of products from which two forms of monooxygenated species Ru(bpy)(2)(N,N-dimethylperoxydithiocarbamate-S,S), 2a, and Ru(bpy)(2)(N,N-dimethylperoxydithiocarbamate-O,S), 2b, and an S-extruded product, Ru(bpy)(2)(N,N-dimethylmonothiocarbamate)(+), 4, have been isolated as PF(6)(-) salts. The S,S-bound monooxygenate is unstable over time toward either O-atom-transfer reactions via disproportionation or reaction with phosphines or S-extrusion yielding complex 4 in which the thiocarbamate is bonded solely through the remaining S atom. All the complexes have been characterized by (1)H NMR, UV-vis, and mass spectroscopies, and all but the highly reactive 2a structurally determined by X-ray crystallography.

Disulfiram Facilitates Intracellular Cu Uptake and Induces Apoptosis in Human Melanoma Cells

“…In this regard, sulfur oxygenation and extrusion have been proposed as modes of the xenobiotic activation of DSF 11,12 and also as possible sources of its neurotoxicity . We have recently shown that similar sulfur oxygenation and extrusion may occur within a metal−DTC complex …”

Ruthenium Complexes with Dithiophosphonates [Ar(RO)PS2]−and [Fc(RO)PS2]−(Ar =p-CH3OC6H4, Fc = Fe(η5-C5H4)(η5-C5H5))

“…Ruthenium−sulfur complexes with sulfur-donor ligands are well known for their industrial applications in hydrodesulfurization (HDS) and related processes, , partly because of the high catalytic activity of RuS 2 in various hydrogenation processes. , The chemistry of ruthenium complexes with dithioacid-based ligands such as dithiocarbamate and dithiocarbonate has been the subject of continuous study to date; − however, the corresponding chemistry of dithiophosphate and dithiophosphonate has not been well developed. , Indeed, thiophosphorus species are an important class of sulfur-donor ligands . For example, the notable Lawesson’s dimer [( p -C 6 H 4 OMe)P(S)(μ-S)] 2 can undergo a ring-opening reaction by nucleophilic attack under suitable conditions, resulting in formation of the typical dithiophosphate and dithiophosphonate ligands. − Even though the synthesis and characterization of thiophosphorus ligands [(RO) 2 PS 2 ] − and [(RO)RPS 2 ] − of a few transition metal derivatives have been investigated in depth, − very little is known about the chemistry of ruthenium-dithiophosphonate and -dithiophosphonate complexes. , Similarly, although the coordinative behavior of ferrocenyl-dithiophosphonate [FcP(OR)S 2 ] − (R = Me, Et, i -Pr, and CH 2 C 6 H 4 N 3 , Fc = Fe(η 5 -C 5 H 4 )(η 5 -C 5 H 5 )) with transition metals was recently studied by Woollins and Süss-Fink et al, − no ruthenium complex with ferrocenyl-phosphonodithiolate as a dithio ligand has been reported to date.…”

Mechanistic Investigations of Photoinduced Oxygenation of Ru(II) Bis-bipyridyl Flavonolate Complexes

“…Often times, [Ru II (bpy) 2 L] 2+ complexes are utilized to initiate such photochemical redox reactions due to well-characterized electron transfer reactivity from long-lived luminescent states. 27 The general family of low spin d 6 [Ru II (bpy) 2 L] 2+ complexes is also quite inert, which allows characterization of unusual ligand-based reactivity; we have used such complexes to characterize products of O atom exchange and S atom extrusion reactions of Ru-bound dithiocarbamates, 28 as well as oxidative and photoinduced C− H activation of Ru-bound heterocycles. 29,30 We recently reported that photooxygenation of a Ru(II) flavonolate complex, using excitation at longer wavelengths than 400 nm, generates a unique Ru-bound 2-benzoatophenylglyoxylate (Ru-bpg) complex resulting from a 1,2 addition pathway, shown in Scheme 2, whereas broad-band excitation yields product mixtures derived from 1,3-addition and loss of CO. 31 In this report, we investigate the possible mechanistic pathways of this reactivity using a series of analogous Ru(II) bis-bipyridyl flavonolate complexes, [Ru II…”