Mass spectral and thermogravimetric studies of some iron(III) binuclear complexes with bridging thiuram disulfide ligands

Abstract

Mass spectral and thermal studies by TG and DTG of some iron(Ill) binuclear complexes of the general type Fez(R2dte)2(tds')X~X~ have been carried out to determine their modes of decomposition. Fragmentation patterns are given and possible mechanisms are discussed.In addition to the variety of products formed [1][2][3][4] during the reaction of iron(Ill) halobisdithiocarbamates, [Fe(Rzdtc)2X ], with halogens, X' 2, some novel homobinuclear iron(Ill) complexes with two different coordination spheres around the magnetic centers have also been synthesized and studied [5], The formation of these products, formulated as Fe2(R2dtc)2(tds~ [R = Me; R 2 = Pyrr; X = CI, Br; and X' = Br, I], depends on the natures of both the molecular halogen and the reagent complex, as well as on the reaction conditions. In particular, the proposed mechanism [5] which accounts for the synthesis of these compounds involves as a first step the formation of the corresponding dihalide-bridged dimers, [Fe(R2dtc)zX]2(/I-X'2). Analogous iron(Ill) complexes have already been isolated and their structures were established on the basis of spectroscopic [1,3, 4] and X-ray crystal structure [6] determination methods, as well as the results of thermoanalytical studies [7]. Depending on the redox capacities of both the halogens and the dithiocarbamato ligands, an intramolecular electron transfer could take place resulting in the oxidation of half of the dithiocarbamate groups into thiuram disulfide. In this case. the dimeric compounds studied in the present paper are formed.Continuing our interest in the thermal investigation of metal dithiocarbamate complexes [7][8][9][10], we report in this paper results concerning mass spectral and thermogravimetric studies of complexes Fe2(R2dtc)z(tds~ The E* values for the main decomposition stage, derived from the Piloyan method [11], TTN calculations [12], and a proposed mechanism of the decomposition are also reported and discussed.