Dithiolates interactions

At the turn of this century it was realized that carrier generation was also possible between the HOMO and LUMO band even in neutral single-component materials assuming that there was a small HOMO-LUMO gap and conduction paths have been associated with the presence of large transverse intermolecular interactions. The most relevant examples of single-component molecular conductors are the mononuclear M(dithiolate)2 (M = Co, Ni, Cu, Au) complexes with... 

Complexes with R = Me, Ph, Mes have been isolated and fully characterized including structural studies. As judged from the Au- -Au distances, the aurophilic interactions between the cations are at best very weak.222 Salts with the cations [(CyNC)2Au]+ and [(tBuNC)2Au]+ and the [(C6H4S2)2Au] anion were obtained in the reaction of the (RNC)AuCl complexes with dithiocatechol 1,2-C6H4(SH)2.223 The reaction of this dithiol with 2 equiv. each of... 

F.E. Inscore, R. McNaughton, B.L. Westcott, M.E. Helton, R. Jones, I.K. Dhawan, J.H. Enemark, and M.L. Kirk, Spectroscopic evidence for a unique bonding interaction in oxo-molybdenum dithiolate complexes implications for sigma electron transfer pathways in the pyranopterin dithiolate centers of enzymes. Inorg. Chem. 38, 1401-1410 (1999). 

A polymeric structure is also observed in the adduct LE 2I2 (LE = 4,5-6z s(bromomethyl)l,3-dithiole-2-thione). LE-I2- I2 bent-shaped units, which are typical in discrete extended spoke adducts with 1 2 (LE/I2) stoichiometry, are joined head-to-tail by soft-soft I- -I interactions involving the terminal iodide atom of the LE-I2 moiety and the terminal iodide atom of the second coordinated di-iodine molecule.37... 

Interestingly, the introduction of two bromomethyl functions in 4- and 5-positions of ethylen-l,3-dithiole-2-thione leads to a packing determined by weak interactions involving also the bromine atoms. One I2 molecule behaves as an acceptor towards S and as donor towards the second I2 molecule, which in turn behaves as donor towards the a c Br orbital (Figure 13). Intermolecu-lar S- -Br, CFF Br and L -I contacts make up a three-dimensional network.480 Reaction of 5,5-dimethyl-2-selenoxoimidazoline-4-one with iodine provided the first structurally characterised compound of the type [RR C Se — I-I].32 The Se-I bond is shorter (269.9 pm) and the I-I contacts are longer (296.2 pm) than in 1 1 adducts of dialkylselenides with iodine (see Chapter 8.2). 

A singlet-triplet behavior is found for those complexes such as [CpNi(oxdt)] [71]or [CpNi(F2pdt)] [72] associated into dyads (Fig. 12), where the strong distortions from planarity of the dithiolate ligands hinder any other interdyad intermolecular contacts. The large Ni S and S S intermolecular distances lead to weak intermolecular interactions with / values of —29 or —8 cnC1 for [CpNi(oxdt)] and [CpNi(F2pdt)] respectively. 

Several studies suggest that LA and DHLA form complexes with metals (Mn2+, Cu2+, Zn2+, Cd2+, and Fe2+/Fe3+) [215-218]. However, in detailed study of the interaction of LA and DHLA with iron ions no formation of iron LA complexes was found [217]. As vicinal dithiol, DHLA must undoubtedly form metal complexes. However, the high prooxidant activity of DHLA makes these complexes, especially with transition metals, highly unstable. Indeed, it was found that the Fe2+-DHLA complex is formed only under anerobic conditions and it is rapidly converted into Fe3+ DHLA complex, which in turn decomposed into Fe2+ and LA [217]. Because of this, the Fe3+/DHLA system may initiate the formation of hydroxyl radicals in the presence of hydrogen peroxide through the Fenton reaction. Lodge et al. [218] proposed that the formation of Cu2+ DHLA complex suppressed LDL oxidation. However, these authors also found that this complex is unstable and may be prooxidative due to the intracomplex reduction of Cu2+ ion. 

Structurally similar 5-chloro-l,2-dithiole-3-thiones 97 were obtained upon treatment of N-(2-phthalimidoethyl)-N-alkylisopropylamines with sulfur monochloride and DABCO and a final reaction with tiiethylamine (20030L929). The stability of thiones 97 is explained by the dipole-dipole interaction between the electron-rich l,2-dithiole-3-thione ring and electron-poor phthalimido groups (Scheme 48). 

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