Dithiocarbamates are highly versatile mono-anionic chelating ligands which form stable complexes with all the transition elements and also the majority of main group, lanthanide and actinide elements. They are easily prepared from primary or secondary amines and depending upon the nature of the cation can show good solubility in water or organic solvents. They are related to the thiuram disulfides by a one-electron redox process (followed by dimerisation via sulfursulfur bond formation) which is easily carried out upon addition of iodide or ferric salts. Dithiocarbamates are lipophilic and generally bind to metals in a symmetrical chelate fashion but examples of other coordination modes are known, the monodentate and anisobidentate modes being most prevalent. They are planar sterically non-demanding ligands which can be electronically tuned by judicious choice of substituents. They stabilize metals in a wide range of oxidation states, this being attributed to the existence of soft dithiocarbamate and hard thioureide resonance forms, the latter formally resulting from delocalization of the nitrogen lone pair onto the sulfurs, and consequently their complexes tend to have a rich electrochemistry. Tetraethyl thiuramdisulfide (disulfiram or antabuse) has been used as a drug since the 1950s but it is only recently that dithiocarbamate complexes have been explored within the medicinal domain. Over the past two decades anti-cancer activity has been noted for gold and copper complexes, technetium and copper complexes have been used in PET-imaging, dithiocarbamates have been used to treat acute cadmium poisoning and copper complexes also have been investigated as SOD inhibitors.

Reactions of Fe₂(CO)₆(μ-pdt) (pdt = SCH₂CH₂CH₂S) with aminodiphosphines Ph₂PN(R)PPh₂ (R = allyl, ⁱPr, ⁱBu, p-tolyl, H) have been carried out under different conditions. At room temperature in MeCN with added Me₃NO·2H₂O, dibasal chelate complexes Fe₂(CO)₄{κ²-Ph₂PN(R)PPh₂}(μ-pdt) are formed, while in refluxing toluene bridge isomers Fe₂(CO)₄{μ-Ph₂PN(R)PPh₂}(μ-pdt) are the major products. Separate studies have shown that chelate complexes convert to the bridge isomers at higher temperatures. Two pairs of bridge and chelate isomers (R = allyl, ⁱPr) have been crystallographically characterised together with Fe₂(CO)₄{μ-Ph₂PN(H)PPh₂}(μ-pdt). Chelate complexes adopt the dibasal diphosphine arrangement in the solid state and exhibit very small P–Fe–P bite-angles, while the bridge complexes adopt the expected cisoid dibasal geometry. Density functional calculations have been carried out on the chelate and bridge isomers of the model compound Fe₂(CO)₄{Ph₂PN(Me)PPh₂}(μ-pdt) and reveal that the bridge isomer is thermodynamically favourable relative to the chelate isomers that are isoenergetic. The HOMO in each of the three isomers exhibits significant metal–metal bonding character, supporting a site-specific protonation of the iron–iron bond upon treatment with acid. Addition of HBF₄·Et₂O to the Fe₂(CO)₄{κ²-Ph₂PN(allyl)PPh₂}(μ-pdt) results in the clean formation of the corresponding dibasal hydride complex [Fe₂(CO)₄{κ²-Ph₂PN(allyl)PPh₂}(μ-H)(μ-pdt)][BF₄], with spectroscopic measurements revealing the intermediate formation of a basal–apical isomer. A crystallographic study reveals that there are only very small metric changes upon protonation. In contrast, the bridge isomers react more slowly to form unstable species that cannot be isolated. Electrochemical and electrocatalysis studies have been carried out on the isomers of Fe₂(CO)₄{Ph₂PN(allyl)PPh₂}(μ-pdt). Electron accession is predicted to occur at an orbital that is anti-bonding with respect to the two metal centres based on the DFT calculations. The LUMO in the isomeric model compounds is similar in nature and is best described as an antibonding Fe–Fe interaction that contains differing amounts of aryl π* contributions from the ancillary PNP ligand. The proton reduction catalysis observed under electrochemical conditions at ca. −1.55 V is discussed as a function of the initial isomer and a mechanism that involves an initial protonation step involving the iron–iron bond. The measured CV currents were higher at this potential for the chelating complex, indicating faster turnover. Digital simulations showed that the faster rate of catalysis of the chelating complex can be traced to its greater propensity for protonation. This supports the theory that asymmetric distribution of electron density along the iron–iron bond leads to faster catalysis for models of the Fe–Fe hydrogenase active site.

The diiron complex Fe ₂ (CO) ₄ (μ-dppf)(μ-pdt) is an active catalyst for both the reduction of protons to give hydrogen and also the reverse oxidation of hydrogen and thus mimics hydrogenases which are able to catalyse both reactions.

Square-planar nickel bis(dithiocarbamate) complexes, [Ni(S₂CNR₂)₂], have been prepared and utilised as single source precursors to nanoparticulate nickel sulfides. While they are stable in the solid-state to around 300 °C, heating in oleylamine at 230 °C, 5 mM solutions afford pure α-NiS, where the outcome is independent of the substituents. DFT calculations show an electronic effect rather than steric hindrance influences the resulting particle size. Decomposition of the iso-butyl derivative, [Ni(S₂CNⁱBu₂)₂], has been studied in detail. There is a temperature-dependence of the phase of the nickel sulfide formed. At low temperatures (150 °C), pure α-NiS is formed. Upon raising the temperature, increasing amounts of β-NiS are produced and at 280 °C this is formed in pure form. A range of concentrations (from 5–50 mM) was also investigated at 180 °C and while in all cases pure α-NiS was formed, particle sizes varied significantly. Thus at low concentrations average particle sizes were ca. 100 nm, but at higher concentrations they increased to ca. 150 nm. The addition of two equivalents of tetra-iso-butyl thiuram disulfide, (ⁱBu₂NCS₂)₂, to the decomposition mixture was found to influence the material formed. At 230 °C and above, α-NiS was generated, in contrast to the results found without added thiuram disulfide, suggesting that addition of (ⁱBu₂NCS₂)₂ stabilises the metastable α-NiS phase. At low temperatures (150–180 °C) and concentrations (5 mM), mixtures of α-NiS and Ni₃S₄, result. A growing proportion of Ni₃S₄ is noted upon increasing precursor concentration to 10 mM. At 20 mM a metastable phase of nickel sulfide, NiS₂ is formed and as the concentration is increased, α-NiS appears alongside NiS₂. Reasons for these variations are discussed.