Dithiocarbamates (DTC) are bidentate organic ligands capable of binding to various metals. First synthesized in 1964, the cis-dicarbonyl-bis(diorganodithiocarbamato)iron(II) complex (Fe(CO)2(S2CNRR’)2) continues to provide a wealth of information regarding organometallic bonding. Recent thermogravimetric analysis (TGA) studies of several of these iron dithiocarbamates were performed in order to provide insight into the thermal decomposition of metal-DTC complexes. It was expected that these complexes would decompose by first losing a carbonyl (CO) ligand, followed by dithiocarbamate ligand fragments, ultimately resulting in the formation of iron sulfides and/or iron. Data appeared to show that mass loss corresponding to CO ligands was dependent on the rate of heating; a rate of 20°C/min seemed to correspond to the simultaneous loss of the two CO ligands, while a rate of 5°C/min seemed to correspond to the stepwise, consecutive loss of the two CO ligands. The stepwise loss implies the formation of a five-coordinate intermediate, Fe(CO)(S2CNRR’)2 and/or a bridged dimer of this five-coordinate intermediate, (Fe(CO)(S2CNRR’)2)2. This work aims to model the thermal decomposition mechanism of iron dithiocarbamates. Density Functional Theory calculations of minimum energy paths are performed for both decompositions: the stepwise loss of CO and the simultaneous loss of CO. Effects of different diorgano substituents is also discussed.

Thermal decomposition of iron dithiocarbamates

249th National Meeting (2015)

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