Synthesis, Crystal Structure and Spectroscopic Studies of New Charge Transfer Compounds Obtained by Reaction of TTF and
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SYNTHESIS, CRYSTAL STRUCTURE AND SPECTROSCOPIC STUDIES OF NEW CHARGE TRANSFER COMPOUNDS OBTAINED BY REACTION OF TTF AND THE POLYOXOANION [Mo 6 0 1 9 ]C.BELLITTO*, D.ATTANASIO, M.BONAMICO, V.FARES, P.IMPERATORI, S.PATRIZIO. Istituto ITSE - C.N.R., Area della Ricerca di Roma, Via Salaria Km. 29.5, C.P.10, 1-00016 Monterotondo Staz., (Roma), Italy. ABSTRACT. Two different tetrathiafulvalene radical cation salts of the [Mo 6 019] polyoxoanion have been isolated and characterized. Compound 1 corresponds to the chemical formula (TTF) 3 [Mo 6 Ol9]. The crystal structure shows a 1D stack of the donor TTF molecule, and each stack fits into channels formed by the anions. Within the stack a chain of trimers is identified, the inter-trimeric distance being 3.51 A. The I.R., electronic and XPS spectra suggest the compound to be a mixed-valence 4salý. Týe electrical conductivity at room temperature is a = 100 cm-. Compound 2 corresponds to the chemical formula (TTF) 2[Mo 6 O1 9 ]. The compound consists of isolated (TTF )2 dimers, interspersed with the polyoxoanions. In agreement with this crystal structure the compound is a diamagnetic insulator. INTRODUCTION. Low-dimensional synthetic metals based on the one-electron organic donor tetrathiafulvalene, TTF, have studied extensively in the last decade [i]. Less attention has been paid to the TTF - derivatives, where the acceptor molecule is a transition metal complex or an inorganic molecular cluster, possibly in the mixed-valence state. The few examples reported in the literature show interesting electrical and magnetic properties [2,3]. Recently, we have reported a series of organic-inorganic materials made by TTF molecule and square planar inorganic metal (II) 1,2 dithio-oxalato S,S' anions [4]. With the aim of exploring this chemistry we have decided to study the reaction of several donor molecules derived from TTF with Phe polyoxometalates anions, having general formula [M6 0 1 9] I where M = Mo,W and n = 2,3. The present paper reports the preparation, the crystal structures and the spectroscopic properties of two new compounds: (TTF) 3 [M°6019]
1
(TTF) 2 [Mo 6O19]
2
EXPERIMENTAL. Crystal Growth of (TTF)
3
[Mo 6 0 9 ]
(1).
A 80 cm3 U-shaped glass cell with the two electrolytic compartments, separated by a sintered glass wall, porosity G4, was used. The solutions used for the electrosynthesis were previously degassed with argon. The Pt electrodes consisted of 0.5 mm diameter rods for both the anode and for the cathode. The ethylammonium salt of the Mo polyoxoanion (0.080 g) was Mat. Res. Soc. Symp. Proc. Vol. 173. ©1990 Materials Research Society
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dissolved in acetonitrile 70 cm 3 , and 40 cm 3 of this solution was placed in the cathodic compartment. The anodic compartment contained an acetonitrile-1,1,2 trichlorfethane solution (30 cm ) of neutral TTF (0.020 g) and 10 cm of the acetonitrile solution of the inorganic salt. Electrodes were immersed in the solution, to a depth of 2.5 cm, through air tight stogpers. The synthesis was carried out at d.c. current of 1
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