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Transition metal bis-dithiolene complexes based on extended ligands with tetrathiafulvalene and thiophene moieties: New sigle-component molecular moieties

Nunes, J. ; Figueira, M. ; Belo, D. ; Santos, I. C. ; Lopes, E. B. ; Henriques, R. T. ; Gancedo, J. ; Veciana, J. ; Rovira, C. ; Almeida, M.

Chemistry A. European Journal Vol. 13, Nº 35, pp. 9841 - 9849, August, 2007.

ISSN (print): 0947-6539
ISSN (online): 0947-6539

Journal Impact Factor: 5,454 (in 2008)

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The gold and nickel bisdithiolene complexes based on new highly extended ligands incorporating fused tetrathiafulvalene and thiophene moieties (a.-tdt=thiophenetetrathiafulvalenedithiolate and dtdt = dihydrothiophenetetrathiafulvalenedithiolate), were prepared and characterised by using cyclic voltammetry, single crystal X-ray diffraction, EPR, magnetic susceptibility and electrical transport measurements. These complexes, initially obtained under anaerobic conditions as diamagnetic gold monoanic [nBu(4)N][Au(alpha-tdt)(2)] (4), [nBU(4)N][Au-(dtdt)(2)] (3) and nickel dianionic species [nBu(4)N][Au(alpha-tdt)(2)] (8), [nBU(4)N][Au-(dtdt)(2)] (7), can be easily oxidised to the stable neutral state just by air or iodine exposure. The monoanionic complexes crystallise in at least two polymorphs, all of which have good cation and anion segregation in alternated layers, the anion layers making a dense 2D network of short S center dot center dot center dot S contacts. All of the neutral complexes, obtained as microcrystalline or quasi amorphous fine powder, present relatively large magnetic susceptibilities that correspond to effective magnetic moments in the range 1-3 mu(B) indicative of high spin states and very high electrical conductivity that in case of the Ni compound can reach sigma(RT)approximate to 250 S cm(-1) with a clear metallic behaviour. These compounds are new examples of the still rare single-component molecular metals.