Dialkyldithiocarbamate Complexes Research Articles

Synthesis of diaryl dithiocarbamate complexes of zinc and their uses as single source precursors for nanoscale ZnS

Diaryldithiocarbamate complexes, [Zn(S2CNAr2)2], have been prepared with a view to comparing their structures, reactivity and thermally-promoted degradation with respect to the well-studied dialkyl-derivatives. In the solid-state both [Zn{S2CN(p-tol)2}2] and [Zn{S2CN(p-anisyl)2}2] are monomeric with a distorted tetrahedral Zn(II) centre, but somewhat unexpectedly, the bulkier naphthyl-derivative [Zn{S2CN(2-nap)2}2]2 forms dimeric pairs with five-coordinate Zn(II) centres. Preliminary reactivity studies on [Zn{S2CN(p-tol)2}2] suggests that it binds amines and cyclic amines in a similar fashion to the dialkyl complexes and can achieve six-coordination as shown in the molecular structure of [Zn{S2CN(p-tol)2}2(2,2′-bipy)]. The thermal decomposition of [Zn{S2CN(p-tol)2}2] was studied in oleylamine solution by both heat-up and hot-injection methods. Nanorods of ZnS were produced in both cases with average dimensions of 17 × 2.1 nm and 11 × 3.5 nm respectively, being significantly shorter than those produced from [Zn(S2CNiBu2)2] under similar conditions. This is tentatively attributed to the differing rates of amine-exchange between diaryl- and dialkyl dithiocarbamate (DTC) complexes and/or their differing rates of DTC loss following amine-exchange. The solid-state decomposition of [Zn{S2CN(p-tol)2}2] has also been studied at 450 °C under argon affording irregular and large (10–300 µm) sheet-like particles of wurtzite.

A General Route for Growing Metal Sulfides onto Graphene Oxide and Exfoliated Graphite Oxide.

Graphene-based materials are elective materials for a number of technologies due to their unique properties. Also, semiconductor nanocrystals have been extensively explored due to their size-dependent properties that make them useful for several applications. By coupling both types of materials, new applications are envisaged that explore the synergistic properties in such hybrid nanostructures. This research reports a general wet chemistry method to prepare graphene oxide (GO) sheets decorated with nanophases of semiconductor metal sulfides. This method allows the in situ growth of metal sulfides onto GO by using metal dialkyldithiocarbamate complexes as single-molecule precursors. In particular, the role of GO as heterogeneous substrate for the growth of semiconductor nanocrystals was investigated by using Raman spectroscopic and imaging methods. The method was further extended to other graphene-based materials, which are easily prepared in a larger scale, such as exfoliated graphite oxide (EGO).

Adducts of zinc and copper(II) dialkyldithiocarbamate complexes with dialkylamines: Synthesis, EPR, and 13C and 15N CP/MAS NMR

Crystalline adducts of zinc and copper(II) dithiocarbamate (Dtc) complexes with dialkylamines [M(NHR′2)(S2CNR2)2] (M = Zn, 63Cu, 65Cu; R = CH3, C2H5, or R2 = (CH2)4O; R′ = C2H5, C3H7) have been preparatively isolated. The structures and spectral properties of the adducts have been studied by EPR and 13C and 15N MAS NMR. Chemisorption of bases on powders of dinuclear dithiocarbamates leads to their dissociation into monomeric adducts. Computer simulation demonstrates that the experimental EPR spectra of isotope-substituted copper(II) adducts have an individual character. The geometry of the copper polyhedra is intermediate between a trigonal bipyramid (TBP) and a tetragonal pyramid (TP). The TBP and TP contributions have been quantified based on EPR data. 13C and 15N MAS NMR data show that the Dtc ligands incorporated into the zinc adduct molecule are structurally nonequivalent. The dependence of the isotropic 15N chemical shifts of the Dtc groups on the alkyl substituents at the nitrogen atom is interpreted based on the concept of joint manifestation of the (+)inductive effect of the alkyl substituents and the mesomeric effect of the Dtc groups.

Oxygenation of Zinc Dialkyldithiocarbamate Complexes: Isolation, Characterization, and Reactivity of the Stoichiometric Oxygenates

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.

Oxazoline chemistry IX. Synthesis and characterisation of the first Zinc oxazoline dialkyldithiocarbamato complexes; X-ray crystal structure determinations of [Zn(S 2CNR 2-κ 2S) 2(2-R′-4,4-R″-2-oxazoline-κ 1N)] (R = R′ = Me, R″ = H; R = Et, R′ = Me, Et or Ph, R″ = H; R = Bz; R′ = R″ = Me)

The synthesis and characterisation (NMR, IR, X-ray diffraction and elemental analysis) of a series of zinc dialkyldithiocarbamato complexes incorporating a monodentate oxazoline ligand are described. These compounds represent the first known examples of oxazolines that are bound to a [Zn(S 2CNR 2) 2] fragment. The syntheses of the title materials involves the treatment of solutions of [Zn(S 2CNR 2) 2] n (R = Me: 1, Et: 2 or benzyl (Bz): 3) with oxazolines (L) of general formula 2-R′-4,4-R″-2-oxazoline (R′ = Me, Et or Ph; R″ = H or Me). The compounds can be isolated in yields ranging from 17% to 82% and all of the complexes are assumed to be mononuclear species of general formula [Zn(S 2CNR 2-κ 2 S) 2(L)]. The nature of the bonding in several examples has been further elucidated in the solid-state by single crystal X-ray diffraction; specifically the cases of R = Me, L = 2-methyl-2-oxazoline: 12; R = Et, L = 2-R′-2-oxazoline: R′ = Me: 9, Et: 10 or Ph: 11 and R = Bz, L = 2,4,4-trimethyl-2-oxazoline: 16. The structurally characterised materials contain two chelating dialkyldithiocarbamato groups and a single oxazoline ligand bound through the N-atom. The disposition of donor atoms around the formally Zn(II) metal centre is best described as distorted trigonal bipyramidal. Complex 16 is the first known N-donor complex of 3 to be fully characterised. In case of the common commercial oxazoline, viz. 4,4-dimethyl-2-phenyl-2-oxazoline, none of the zinc compounds tested forms a stable complex. Some aspects of the steric and electronic effects on oxazoline adduct formation within this series of complexes is discussed. The relationship of these new compounds to other structurally similar and industrially relevant zinc dialkyldithiocarbamate complexes is also detailed.

Thermal decomposition of 5-amino-2-thiol-1,3,4-thiadiazole (<Emphasis Type=?Italic?>HATT</Emphasis>) Cu(II) and Zn(II) complexes

The mercury(II) bis(dialkyldithiocarbamate) complexes, Hg(S 2 CN-R 2 ) 2 , in which R =ethyl, n -propyl, n -butyl and iso-butyl were characterized by TG, DSC, FTIR and elemental analysis. The TG curves presented two thermal decomposition stages; the first stage can be attributed to the partial decomposition of ligand and also to mercury sulfide decomposition. The second stage is representative for the decomposition of ligand fragments. The overlaid TG/DSC curves indicated that the decomposition of the complexes takes place the liquid phase. According to the isothermal kinetic data the phase-boundary controlled kinetic models describes the best the decomposition of complexes. The data obtained by the Ozawa method suggest the following stability order for the complexes: i Bu> n Pr> n Bu>Et.

Determination of zinc dialkyldithiocarbamates in latex condoms.

A simple high-performance liquid chromatographic (HPLC) assay is developed for measuring zinc dialkyldithiocarbamate (DTC) levels in latex condoms. After extraction of 14 different brands of latex condoms in acetonitrile, aliquots of the extracts are subjected to a preliminary screening assay by treatment with cobalt chloride and measurement of UV absorption at 320 nm, which results in the identification of 6 DTC-containing samples. Prior to analysis by HPLC, zinc dimethyldithiocarbamate (ZDMC) or zinc diethyldithiocarbamate (ZDEC) is added to the extracts in order to block transmetalation reactions with the analytes of interest. A reversed-phase C(18) column, with gradient elution and UV detection at 260 nm, is used to measure the zinc DTCs. The limits of detection for ZDEC and zinc dibutyldithiocarbamate (ZDBC) are 5 and 10 micro g/mL. Levels of ZDBC and ZDEC range from not detectable to 3.31 and 1.79 mg/condom, respectively. Total protein and latex allergenic protein levels are determined and range from 98 to 776 and 0.01 to 14.04 micro g/unit, respectively, but are not related to the level of ZDBC or ZDEC. This methodology provides both screening and specific tools for the determination of unstable zinc DTC complexes in latex products.

Cerium(III) dialkyl dithiocarbamates from [Ce[N(SiMe3)2]3] and tetraalkylthiuram disulfides, and [Ce(kappa2-S2CNEt2)4] from the Ce(III) precursor; Tb(III) and Nd(III) analogues.

The synthesis and characterisation of the first neutral cerium dialkyl dithiocarbamate complexes, using a novel oxidative displacement of the amido ligands of [Ce[N(SiMe3)2]3] by tetraalkylthiuram disulfides [R2NC(S)S]2(R = Me, Et) in thf solution, are reported. In the absence of other donors, the complexes [Ce(kappa2-S2CNMe2)3(thf)2] and Ce(kappa2-S2CNEt2)3) 3 were obtained. The addition of a polypyridyl ligand allowed easy access to a range of complexes of general formula [Ce(kappa2-S2CNR2)3(L[intersection]L)][R = Me and L([intersection])L = 2,2'-bipy (4), or 4,7-diphenyl-1,10-phenanthroline (6); or R = Et and L[intersection]L = 2,2'-bipy (5)]. Brief exposure of the Ce(III) dithiocarbamate to oxygen gas afforded in high yield the diamagnetic, crystalline Ce(IV) dithiocarbamate [Ce(kappa2-S2CNEt2)4)] 7. The neodymium (8) and terbium (10) complexes, isoleptic with 2, were prepared from the appropriate 4f metal (Ln) bis(trimethylsilyl)amide [Ln[pN(SiMe3)2]3][Ln = Nd or Tb (9)] and [Me2NC(S)S]2. The structures of the crystalline complexes, 2, 4, 6, 7, 9 and 10 have been determined by X-ray crystallography. Some evidence has been obtained for the formation of the cerium(IV) complex Ce[N(SiMe3)2]2(kappa2-S2CNMe2)2. The cerium(IV) complex 7 has the metal coordinated to eight sulfur atoms of four planar chelating S2CNC2 moities and its geometry is intermediate between dodecahedral and square prismatic; the mean Ce-S bond length of 2.803 A in 7 compares with the 2.950 A in the Ce(III) complex 2.

Thermal and structural characterization of a series of homoleptic Cu(II) dialkyldithiocarbamate complexes: bigger is only marginally better for potential MOCVD performance

A series of Cu(II) dialkyldithiocarbamate complexes, Cu(S 2CNRR′) 2, with R=R′= n-Bu ( 1); i-Bu ( 2); c-Hex ( 3); CH 2Ph ( 4); R= n-Bu, R′=Et ( 5); R= n-Pr, R′= c-PrCH 2 ( 6); R=R′= n-Pr ( 7); i-Pr ( 8); allyl ( 9), were prepared. The thermal properties of the complexes were investigated to determine if their potential performance in chemical vapor deposition processes was affected by the nature of the peripheral substituents of the ancillary ligands. Modest gains in volatility were noted for 2 and 7 over the most often utilized complex with R=R′=Et, while 1 and 8 had thermal parameters and stability comparable to this standard. Unsymmetrical substitution, such as in 5, also improved volatility, with some loss of stability for this particular compound. X-ray diffraction studies of complexes 1– 6 suggested that long range Cu⋯S interactions in the solid-state have little bearing on the thermal properties of this class of Cu(II) complexes.

Heteroligand Lanthanide Dialkyldithiocarbamate Complexes with 1,10-Phenanthroline: A New Approach to Synthesis and Application for the Preparation of Sulfides

A new simple method of synthesis of heteroligand complexes [Ln(Dalkdtc)3Phen] (Ln = Eu or Er; Dalkdtc is the dialkyldithiocarbamate ion, Phen is o-phenanthroline) in an aqueous solution is described; the possibility of using the complexes as initial reagents for the synthesis of rare-earth sulfides is shown.

Charge density distribution and bond characterization of metal dialkyldithiocarbamate complexes (M=Co, Ni)

Electron density distribution of metal dithiocarbamate complexes, Co(S 2CNMe 2) 3 and Ni(S 2CNEt 2) 2, are studied both by single X-ray diffraction method and by theoretical quantum molecular orbital calculation. Bond characterization is made in terms of deformation density, topological analysis on total electron density and Fermi hole distribution. The cobalt(III) ion is coordinated with three ‘chemically equivalent’ planar bidentate ligands. The structure of the complex is like a ‘three-bladed propeller’. The Ni(II) ion is coordinated with two ligands in a square planar fashion. Deformation density distribution and topological analysis based on multipole model and molecular orbital calculations (DFT) are performed. The asphericity in electron density around the metal ion is clearly demonstrated; where local electron density accumulation is found at d π directions but local electron density depletion is found at d σ direction. The agreement between experiment and theory is good. The comparison between ligand dimer (S 2CNEt 2) 2, and metal complexes are made. With the topological analysis, the shape of valence shell charge concentration (VSCC) of each atom is illustrated. The bond characterization is made through topological properties associated with bond critical point (BCP). The linear relationship between the electron density at the bond critical point, ρ( r c), and the bond length leads to the conclusion that ρ( r c) is a good indicator of bond strength. The bond type is determined by the Laplacian at BCP, the total energy density at BCP and the Fermi-hole function.

N, N′-Dialkyldithiocarbamate chelates of indium(III): alternative synthetic routes and thermodynamics characterization

Alternative synthetic routes to prepare N, N′-dialkyldithiocarbamate complexes of indium(III), In(S 2CNR 2) 3 (R = CH 3, C 2H 5, n-C 3H 7, i-C 3H 7, n-C 4H 9 and i-C 4H 9) from the metallic element and from indium monohalides, InX(X = Cl, Br and I) were established. The proposed mechanism of reaction involving InX considering a ligand redistribution reaction of XIn(S 2C–NR 2) 2 initially produced, which could be derived from the insertion of InX into sulfur–sulfur bond of the tetralkylthiuram disulfide. The thermal decomposition of the In(S 2CNR 2) 3 (R = CH 3, C 2H 5, n-C 3H 7, i-C 3H 7, n-C 4H 9 and i-C 4H 9) compounds was investigated by the thermogravimetric technique, where two pathways were detected, depending on the dialkyldithiocarbamato ligand. The first step leads to indium metal, or alternatively In 2S 3, as the final residue for R = C 2H 5, n-C 3H 7, i-C 4H 9 and for R = CH 3, i-C 3H 7, n-C 4H 9, respectively. The corresponding standard molar enthalpies of sublimation of all compounds were determined by means of differential scanning calorimetry and methods of estimation.

Coordinating ability of the heterocycles 1,3-dithia-2-arsa and stiba-cyclopentanes toward sulfur containing ligands, part I. Dialkyl-dithiocarbamate complexes

The heterocyclic compounds ClMS2 (CH2)2 (M = As, Sb) are tested by first time as source of starting materials in the synthesis of complexes. The preparation and characterization of heterocyclic dithiocarbamatesR2NCS2MS2 (CH2)2, (M = As, Sb;R =Me,Et,i-Pr) is reported. Spectroscopic and analytical data suggest a bidentate behavior of the dithiocarbamate entity and the presence of aMS4 core.

The direct electrochemical synthesis of dialkyldithiocarbamate and diethyldithiophosphate complexes of main group and transition metals

Dialkyldithiocarbamate derivatives (R2NCS2)nM of a number of metals (M = Fe, Co, Ni, Cu, Ag, Zn, Cd, In, Tl) have been synthesised in good yield by electrochemical oxidation of appropriate sacrificial anodes in non-aqueous solutions of either the corresponding tetraalkylthiuram disulphide (R2NCS2)2 (R = Me, Et) or a mixture of carbon disulphide plus the secondary amine R2NH (R = Et, i-Pr; R2NH = piperidine). Similar experiments with solutions of (EtO)2P(S)SH (= HL) gave MLn•derivatives (M = Fe, Co, Ni, Cu, Ag, Au, Zn, Cd, Hg, Ga, In, Tl) while in the presence of HL + 1,10-phenanthroline, MLn•phen derivatives were obtained for M = V, Mn, Fe, Co, Zn, and Ga.

Thermal studies on molybdenum(IV) dialkyl dithiocarbamate adducts with pyridine

Spectroscopic, magnetic and analytical studies on the adducts of several molybdenum(IV) dialkyl dithiocarbamate complexes with pyridine have been previously reported. The formula which most closely fits the analyses is Mo 2(dtc) 4·Py 2 (where dtc = di-ethyl. di-n-propyl, di-isopropyl, di-isobutyl and N-methyl-cyclohexyl dithiocarbamates). The study of these adducts using DSC and TG techniques allowed us to determine the degree of thermal stability of these compounds. The DSC curves corresponding to the decomposition of the adducts showed only a single endothermic peak. The mass loss accompanying the endothermic transition corresponded to the loss of two molecules of pyridine with a residue of Mo 2(dtc) 4. From the DSC curves, activation energies have been calculated.

Monodentate dialkyldithiocarbamate complexes of molybdenum(III). The synthesis and X-ray strucural characterization of {HB(3,5-Me 2C 3N 2H) 3}Mo-(S 2CNEt 2)(ν 1-S 2CNEt 42)

Cristallisation dans le systeme triclinique, groupe P1 et sa structure est affinee jusqu'a R=0,043. Coordination pseudooctaedrique autour des atomes Mo

Behaviour of copper(II) and nickel(II) dialkyldithiocarbamates on polar and non-polar stationary phases

Fifteen Dialkyldithiocarbamate complexes each of copper(II) and Ni(II) have been prepared and the retention times of these complexes have been measured on the non-polar OV-101 phase and the polar NGA and OV-225 phases. The relationship has been studied between the retention characteristics of the complexes and their structure. The lenght of the alkyl substituent, regarded as a steric hindrance, turned out to affect the retention of the complexes on the non-polar phases.

Phosphorus-31, cadmium-113 and mercury-199 N.M.R. studies on dithiolate complexes of cadmium and mercury and their phosphine adducts

Phosphorus-31, cadmium-113 and mercury-199 n.m.r. spectra have been recorded for a series of O,O-dialkyldithiophosphate (dtp) and dialkyldithiocarbamate (dtc) complexes of cadmium and mercury in dichloromethane solution. Both types of ligand are labile on the n.m.r. time scale at room temperature, although the exchange of dtc ligands can be slowed at low temperatures. .The complexes interact with tributylphosphine and tricyclohexylphosphine (pcy), but at room temperature the phosphines are also labile. At low temperatures, however, the phosphine exchange becomes slow on the n.m.r. time scale to allow identification of the adducts except for Cd(dtc)2 adducts with PBu3 which are still labile at -110°C. All the data indicate that cadmium has a lower affinity for phosphine than mercury and that dtc ligands are more strongly bound to the metals than dtp ligands.

Syntheses and spectroscopic study of some new mixed-ligand Bi(III) 1,1-dithiolate complexes

The reaction between halogenobis(dialkyldithio-carbamate) complexes of Bi(III) and sodium dialkyldithiocarbamate or potassium O-ethylxanthate yields mixed-ligand Bi(III) 1,1-dithiolate complexes. A series of ten new mixed-ligand complexes have been synthesized and studied spectroscopically. The new complexes have been characterized by elemental analysis, molecular weights, i.r. 1H n.m.r., electronic and mass spectra. From the spectroscopic study it is deduced that the presence of the two types of 1,1-dithiolate ligands does not influence greatly the electronic properties of the complexes compared to those of the corresponding tris(1,1-dithiolate) complexes. It is also deduced that the xanthate group is a chelated ligand weaker than the dithiocarbamate group in the case of the Bi(III) complexes.

Metal ligand bond contraction and possible spin–orbit induced Jahn–Teller distortion in the iron(III) dialkyldithiocarbamate ‘crossover’ system

Comparison of the crystal structure of high- and low-spin iron(III) dialkyldithiocarbamate complexes, [Fe(CS2·NR2)3], reveals (a) the predicted difference (0·1 A) in metal–sulphur bond length and (b) an unusual distortion from D3 to C3 symmetry in the low-spin complex, attributed to spin–orbit interactions in the ground state.