ELSEVIER Synthetic Metals 102 (1999) 1709-1710 Synthesis of new tetrathiafulvalenes with aromatic substituents and related metallic dithiolene complexes E. Cerradaa, J. Garridob, M. Lagunaa , N. Lardiesa, I. Romeob aDepartamento de Quimica Inorganica, lnstituto de Ciencia de Materiales de Aragon, Universidad de Zaragoza- C.S.I.C., 50009 Zaragoza, Spain. bDepartamento de Quimica Aplicada, Universidad Publica de Navarra, E-31006 Pamplona, Spain. Abstract Synthesis of square-planar complexes and the corresponding TTF’s derivatives with 4-(substituted)l,2-dithiolene as ligands can be achieved starting from the corresponding thione or ketone in an ethoxide solution. Complexes of Ni(ll) and Au(lll) have been prepared using 4-(p-Cyanophenyl) and 4-(4-pyridil)l,3-dithiole-2-thione as precursors. Keywords: Heterocycle synthesis, coupling reactions, electrochemical methods 1. Introduction Transition-metal complexes with 1,2-dithiolene ligands have received much attention because of their capacity to give molecular metals and superconductors [l] and more recently because of their potential applications as third- order non-linear optical materials [2,3]. The importance in the chemistry of such square-planar M(dithiolene)2 complexes is due to their ability to overlap with each other including strong electronic interactions between the units, which is a condition to obtain electronic properties, such as conductivity or even unusual magnetic behaviour [4,5]. These M(dithiolene)2 complexes have a similar structure to the tetrathiafulvalene (TTF) and that is the reason for further investigation in these areas [6-l I]. 2. Experimental 4-(p-Cyanophenyl)l,3-dithiole-2-thione (1) and 4-(4- pyridil)-1,3-dithiole-2-thione (2): 4-(p-Cyanophenyl)l,2,3- thiadiazole (0.935 g) or 4-(4-pyridil)l,2,3-thiadiazole (0.815 g) was dissolved in dry MeCN under argon. CS2 (2 mL) and NaH (0.05 g, 60 % mineral oil dispersion) were added. After 2h of stirring orange solids precipitated. Yield(%): 88, 86. 4-(p-Cyanophenyl)l,3-dithiole-2-ketone (3): 1 (0.35 g) was dissolved in CHC13 under argon atmosphere. Hg(02CMe)2 (1.12 g) were added in glacial acetic acid. After 2h of stirring, the white solid was filtered off. The solution was washed with saturated NaHC03 solution and deionised water. The organic phase was dried and concentrated to dryness. Yield: 85 % 4-(4-pyridil)-1,3-dithiole-2-ketone (4): 2 (O.SSSg) was suspended in CHsCN under argon atmosphere. Hg(O&Me)z (2.4 g) were added and the mixture was kept at reflux for 2h. The solution was poured on a short column of silica and eluted with CH&12. Yield: 35 %. 2,6(7)-bis(p-Cyanophenyl)-l,4,5,8-tetrathiafulvalene (5): a) Triethylphosphite was added under dry argon atmosphere to 1 or 3 (0.1 mmol) and refluxed for 3 h. A red solid precipitated, which was filtered off and washed with cyclohexane. Yield: 50 %.- ‘H NMR: 6 = 7.84 (d, J= 7.7 Hz, 2 H), 7.72 (d, 2 H), 7.40 (s, 1H). IR : u (C=N) = 2222 cm-’ - MS (El): m/z (%) = 406 (60). b) 1 (0.235 g) was dissolved in dry toluene and added Co2(CO)s (0.306 g) and refluxed for 2h. The black residue is filtered off, the solution concentrated and cooled, giving rise a red solid which was filtered off.Yield : 40 % 2,6(7)-bis(4-pyridil)-1,4,5,8-tetrathiafulvalene (6):P(OEt)s was added under dry argon to 2 (0.066 g) and refluxed for 3 h. A blue-green solution resulted, which was cromatografied on silica, eluted with cyclohexane and then with acetone. A red solid is obtained. Yield: 20%.- ‘H NMR: 8 = 8.6 (d, J = 6.0 Hz), 8.5 (d, J = 6.0 Hz), 7.5 (d), 7.4 (d), 7.0 (s), 6.5 (s). IR: II (py) = 1590 cm”. 7: 7a (Q = NBu4) 7b (Cl = NEt4): 1 or 3 (0.2 mmol) was suspended in EtOH under argon. NaOEt 0.1 M (6 mL) was added and the mixture was refluxed for 30 min in the case of 1 until no solid remained. QBr (0.1 mmol) were added followed by NiC12.6H20 (0.024 g) giving rise black brown solutions. After 12 h of stirring were concentrated and the addition of diethyl ether afforded the precipitation of black brown solids which were filtered off, washed with deionized water. Yield (%): 60, 70 (7a), 65, 81 (7b).- ‘H NMR: 7a 6 = 7.69 (d, J = 7.5 Hz, 4 H), 7.5 (d, 4 H), 7b 6 = 7.7 (d, J= 7.4 Hz, 4 H), 7.55 (d, 4 H). IR: F (C=N) = 2220 cm-l (7b), 2221 cm-’ (7b) 8: 8a (Q = NBu4) 8b (Q = N(PPh3)2, PPN): a) 1 or 3 (0.2 mmol) was treated as above. Q[AuBr4] (0.2 mmol) was added giving rise brown solids which were filtered off. Yield(%): 65, 75 (8a), 60, 76 (8b).- ‘H NMR : 8a 6 = 7.78 (d, J = 6.9 Hz, 4 H), 7.59 (d, 4 H), 7.0 (s, 2 H). IR: u (C=N) = 2221 (8a), 2223 cm-l (8b). 9: Synthesised as above starting from 2 or 4 (0.2 mmol). A brown solid was obtained. 70 %.-IR:u (py)=1590 cm-‘. 10: 1 (0.023 g) was dissolved in CHzClz and AgCFsSOsL (0.1 mmol) was added. After 1 h of stirring, a yellow solid precipitated Yield: 70 %.- ‘H NMR: 6 = 7.89 (d, J = 8.8 Hz, 2 H), 7.81 (d, 2 H), 8.01 (s, 1H). IR: 2) (C=N) = 2236 cm-‘, II (C=S) = 1022 cm-’ 11: a) 2 (0.021 g) was dissolved in EtOH and AgCFsSOsPPhs (0.052 g) was added. After 2h of stirring, a yellow solid precipitated which was filtered off. Yield: 85 %.- IR: u (Py) = 1600 cm-‘, II (C=S) = 1068, 1042 cm-‘. b) 2 (0.021 g) was dissolved in EtOH and AgCFsSOs (0.025 g) was added and treated as above. Yield: 83 %. 12: 2 (0.021 g) was dissolved in EtOH and AgNOs (0.034 g) was added. After 2h of stirring, a yellow solid precipitated Yield: 80 %. IR:u (C=S) =1058, 1038 cm-‘, u (NO3) = 1384, 1329 cm-‘. II (Py) = 1603 cm-’ 0379-6779/99/$ - see front matter 0 1999 Elsevier Science S.A. All rights reserved. PII: SO379-6779(98)00863-7