Dithiocarbamate Complexes as Single Source Precursors to Nanoscale Binary, Ternary and Quaternary Metal Sulfides

Nanodimensional metal sulfides are a developing class of low-cost materials with potential applications in areas as wide-ranging as energy storage, electrocatalysis, and imaging. An attractive synthetic strategy, which allows careful control over stoichiometry, is the single source precursor (SSP) approach in which well-defined molecular species containing preformed metal-sulfur bonds are heated to decomposition, either in the vapor or solution phase, resulting in facile loss of organics and formation of nanodimensional metal sulfides. By careful control of the precursor, the decomposition environment and addition of surfactants, this approach affords a range of nanocrystalline materials from a library of precursors. Dithiocarbamates (DTCs) are monoanionic chelating ligands that have been known for over a century and find applications in agriculture, medicine, and materials science. They are easily prepared from nontoxic secondary and primary amines and form stable complexes with all elements. Since pioneering work in the late 1980s, the use of DTC complexes as SSPs to a wide range of binary, ternary, and multinary sulfides has been extensively documented. This review maps these developments, from the formation of thin films, often comprised of embedded nanocrystals, to quantum dots coated with organic ligands or shelled by other metal sulfides that show high photoluminescence quantum yields, and a range of other nanomaterials in which both the phase and morphology of the nanocrystals can be engineered, allowing fine-tuning of technologically important physical properties, thus opening up a myriad of potential applications.

On the Coordination Role of Pyridyl-Nitrogen in the Structural Chemistry of Pyridyl-Substituted Dithiocarbamate Ligands

A search of the Cambridge Structural Database was conducted for pyridyl-substituted dithiocarbamate ligands. This entailed molecules containing both an NCS2− residue and pyridyl group(s), in order to study their complexation behavior in their transition metal and main group element crystals, i.e., d- and p-block elements. In all, 73 different structures were identified with 30 distinct dithiocarbamate ligands. As a general observation, the structures of the transition metal dithiocarbamates resembled those of their non-pyridyl derivatives, there being no role for the pyridyl-nitrogen atom in coordination. While the same is true for many main group element dithiocarbamates, a far greater role for coordination of the pyridyl-nitrogen atoms was evident, in particular, for the heavier elements. The participation of pyridyl-nitrogen in coordination often leads to the formation of dimeric aggregates but also one-dimensional chains and two-dimensional arrays. Capricious behaviour in closely related species that adopted very different architectures is noted. Sometimes different molecules comprising the asymmetric-unit of a crystal behave differently. The foregoing suggests this to be an area in early development and is a fertile avenue for systematic research for probing further crystallization outcomes and for the rational generation of supramolecular architectures.

Crystal structure of bis[μ2-(N-(2-hydroxyethyl)-N-methylcarbamodithioato-κS:κS,κS′)]-bis(triethylphosphine-P)-di-silver(I), C20H46Ag2N2O2P2S4

C20H46Ag2N2O2P2S4, triclinic, P1̄ (no. 2), a = 9.3895(1) Å, b = 13.1597(2) Å, c = 13.1803(2) Å, α = 88.119(1)°, β = 86.601(1)°, γ = 70.173(1)°, V = 1529.22(4) Å3, Z = 2, R gt(F) = 0.0162, wR ref(F 2) = 0.0406, T = 100(2) K.

Crystal structure of bis[μ2-(N,N-diethylcarbamodithioato-κS:κS,κS′)]-bis(triethylphosphine-P)-di-silver(I), C22H50Ag2N2P2S4

C22H50Ag2N2P2S4, triclinic, P1̄ (no. 2), a = 9.0672(2) Å, b = 11.2091(3) Å, c = 16.6853(4) Å, α = 91.097(2)°, β = 90.363(2)°, γ = 110.989(2)°, V = 1582.85(7) Å3, Z = 2, R gt(F) = 0.0241, wR ref(F 2) = 0.0653, T = 100(2) K.

Crystal structure of bis[μ2-(pyrrolidine-1-carbodithioato-κS:κS,κS′)]-bis(triethylphosphine-κP)disilver(I), C22H46Ag2N2P2S4

C22H46Ag2N2P2S4, triclinic, P1̄ (no. 2), a = 10.2008(3) Å, b = 12.2058(3) Å, c = 13.2466(4) Å, α = 88.155(2)°, β = 87.256(2)°, γ = 69.324(2)°, V = 1541.12(8) Å3, Z = 2, R gt(F) = 0.0237, wR ref(F 2) = 0.0621, T = 100(2) K.

New main-group ferrocenyldithiocarbamates and conversion to ferrocene oxazolidine-2-thione and -2-one

Three new main-group ferrocenyl dithiocarbamates and a pure cyclised product, 3-ferrocenylmethyl-oxazolidine-2-thione, were isolated using copper powder.

The crystal structure of bis[μ2-(N,N-diethylcarbamodithioato-κS:κS,κS′)] bis[1′-(diphenylphosphino-κP)-1-cyanoferrocene]disilver(I), C56H56Ag2Fe2N4P2S4

C56H56Ag2Fe2N4P2S4, triclinic, P1̄ (no. 2), a = 9.5058(2) Å, b = 10.8362(2) Å, c = 14.3325(3) Å, α = 72.400(1)°, β = 75.241(1)°, γ = 77.132(1)°, V = 1343.71(5) Å3, Z = 1, R gt(F) = 0.0191, wR ref(F 2) = 0.0443, T = 150(2) K.

In vitro anti-bacterial and time kill evaluation of binuclear tricyclohexylphosphanesilver(I) dithiocarbamates, {Cy3PAg(S2CNRR')}2

Four binuclear phosphanesilver(I) dithiocarbamates, {cyclohexyl₃PAg(S₂CNRR')}₂ for R = R' = Et (1), CH₂CH₂ (2), CH₂CH₂OH (3) and R = Me, R' = CH₂CH₂OH (4) have been synthesised and characterised by spectroscopy and crystallography, and feature tri-connective, μ₂-bridging dithiocarbamate ligands and distorted tetrahedral geometries based on PS₃ donor sets. The compounds were evaluated for anti-bacterial activity against a total of 12 clinically important pathogens. Based on minimum inhibitory concentration (MIC) and cell viability tests (human embryonic kidney cells, HEK 293), 1-4 are specifically active against Gram-positive bacteria while demonstrating low toxicity; 3 and 4 are active against methicillin resistant S. aureus (MRSA). Across the series, 4 was most effective and was more active than the standard anti-biotic chloramphenicol. Time kill assays reveal 1-4 to exhibit both time- and concentration-dependent pharmacokinetics against susceptible bacteria. Compound 4 demonstrates rapid (within 2 h) bactericidal activity at 1 and 2 × MIC to reach a maximum decrease of 5.2 log₁₀ CFU/mL against S. aureus (MRSA).

Intermolecular Tl⋯H–C anagostic interactions in luminescent pyridyl functionalized thallium(i) dithiocarbamates

Rare intermolecular C–H⋯Tl anagostic and C–S⋯Tl interactions forming a six-membered chelate ring.