Type

Database

Creator

Date

Thumbnail

Search results

24 records were found.

A perfluorinated tetrathiafulvalene (TTF) derivative 1, that is a bis(vinylenedithio)TTF substituted with -(CF2)3− chains on both ends, is prepared from the reaction of Na2dmit (dmit: 1,3-dithiole-2-thione-4,5-dithiolate) with 1,2-dichlorohexafluorocyclopentene, oxymercuration of the obtained dithiolethione to the corresponding dithiolone and phosphite coupling. An unsymmetrical TTF 2 fused with only one hexafluorocyclopenta[1,2-b]1,4-dithiine moiety is also described together with the X-ray crystal structures and electrochemical properties of 1 and 2. The amphiphilic character provided by the rigid −(CF2)3− moieties in 1 and 2 leads to a strong segregation of the aliphatic fluorinated moieties in the solid state, affording fluorinated columns or bilayer structural motifs. To cite this article: O. Jeannin, M. Fourmigué, C. R. Chimie 9 ...
Two closely related 1:1 salts are obtained upon electrocrystallization of BEDT-TTF (BEDT-TTF: bis(ethylenedithio)tetrathiafulvalene) in the presence of the isosteric [M(tfadt)2]− dithiolene complexes (tfadt: 1-trifluoromethyl-2-cyano-1,2-dithiolato), which essentially differ by their spin state, S = 0 in [Au(tfadt)2]−, S = 1/2 in [Ni(tfadt)2]−. In both [BEDT-TTF][M(tfadt)2] salts, the BEDT-TTF radical cations form chains with a strong lateral overlap and strong antiferromagnetic interactions while the paramagnetic anions in the nickel-containing salt [BEDT-TTF][Ni(tfadt)2] are essentially non-interacting. The structural differences between the nickel and gold complexes are analyzed and discussed.
The well-known influence of long perfluorinated chains on the structures and stability of amphiphilic molecules in liquid crystalline mesophases or mesoscopic micellar arrangements is evaluated here in the realm of crystalline materials based on rigid aromatic molecules bearing only a limited number of CF3 moieties. Tetrathiafulvalene (TTF) derivatives bearing one or two CF3 groups, that is, (Z)- and (E)-(CF3)2TTF ((Z)-1, (E)-1), EDT-TTF-CF3 (2), and EDT-TTF(CF3)2 (3) (EDT=ethylenedithio) are prepared from the 1,3-dipolar reaction of methyl 4,4,4-trifluorotetrolate with ethylenetrithiocarbonate. The structures of neutral (Z)-1, (E)-1, 2, and 3 as indicated by single-crystal X-ray diffraction measurements reveal the recurrent formation of layered structures with a strong segregation of the fluorinated moieties and formation of fluorous ...
The room-temperature (RT) crystal structure of the colbaltocinium salt of the S = 1/2 nickel dithiolene complex [Ni(tfadt)2]-* (tfadt, 2-trifluoromethylacrylonitrile-1,2-dithiolate) is characterized by uniform one-dimensional spin chains of radical anions, separated from each other by the [Cp2Co]+ cations. Both entities exhibit disorder affecting one CF3 and one Cp ring. Upon being cooled from RT (phase A), two successive structural phase transitions lead to tetramerized spins chains with a low-temperature singlet ground state (phase C) with an associated ordering of the CF3 and Cp moieties. An intermediate tetramerized C′ phase is observed during the cooling sweep, in competition with a dimerized chain structure (phase B) upon warming, affording an apparent giant thermal hysteresis loop of 50 K. The phase succession in temperature at ...
A chiral tetrathiafulvalene (1) bearing a binaphtholdimethylene moiety on one side, an ethylenedithio substituent on the other side, is prepared from atropoisomeric (R)-, (S)- and racemic (R,S)-binaphthol. Its oxidation potential (0.49 V vs. SCE) allows for its oxidation with TCNQF4. Crystal structures of the neutral racemic (R,S)-1 and enantiopure (R)-1 were determined together with those of the enantiopure charge-transfer salts formulated as [(R)-1][TCNQF4]*CH2Cl2 and [(S)-1][TCNQF4]*CH2Cl2, the first enantiomeric salts of chiral TTFs with axial chirality. Despite the peculiar geometry adopted by the binaphthyl moieties in the constrained ten-membered ring in 1, stacking of the donor molecules is observed, both in the neutral state and in the TCNQF4 charge transfer salts where the (1)+˙ and (TCNQF4)−˙ radical species are associated, ...
Novel chiral tetrathiafulvalene derivatives incorporating one or two binapthol moieties are described where two flexible (Ar-O)-CH2-CH2-S-(TTF) links generate a large 14-membered ring on one or both sides of the TTF core. The symmetric donor molecule with two chiral binaphthol moieties has been prepared as enantiopure (RR) or (SS) isomer, as well as diastereomeric mixture containing the (RR), (SS), and meso (RS)double bond; length as m-dash(SR) forms. Other unsymmetrically substituted derivatives bearing one single chiral binaphthol substituent on one side were also prepared in their enantiopure (R) and (S) forms and as racemic mixture. X-ray crystal structure determinations of different donor molecules show that the TTF tend to associate into face-to-face dyads with a strong folding of the dithiole rings along the S⋯S hinge while the ...
The ferricinium salt of the anionic, S = 1/2, dithiolene complex [Ni(tfadt)2]- (where tfadt is the asymmetrically substituted 2-(trifluoromethyl)acrylonitrile-1,2-dithiolate) crystallizes at room temperature (rt) into uniform chains of dithiolene complexes, separated by ferricinium cations. Both ionic entities are characterized by disorder affecting one CF3 and one Cp moiety. Above 250 K, this compound displays a Curie-type behavior. At lower temperatures, two first-order transitions around 249 and 137 K are revealed by susceptibility measurements and the observation of hysteresis effects. Crystal structure determinations performed at 230 and 120 K show that the high-temperature transition is associated with an ordering of the CF3 and Cp groups together with a dimerization of the anionic stacks that thus induces a drop of the susceptib...
A comparative investigation on five different Cp2Ti(diselenolene) complexes, i.e. Cp2Ti(Se2C2Z2) (Z = -CO2Me), Cp2Ti[Se2C2Z(CF3)], Cp2Ti(bds) (bds = 1,2-benzene-diselenato), Cp2Ti(dsit) (dsit = 1,3-dithiole-2-thione-4,5-diselenato) and Cp2Ti(ddds) (ddds = 5,6-dihydro-1,4-dithiine-2,3-diselenato) is performed based on structural and variable-temperature NMR data. Preparation of Cp2Ti[Se2C2Z(CF3)] involves the reaction of Cp2TiSe5 with an excess of methyl-4,4,4-trifluorotetrolate while Cp2Ti(bds) is obtained from the bds2− diselenolate and Cp2TiCl2. Their X-ray crystal structures have been determined, showing that Cp2Ti(bds) is not isostructural with the sulfur analog Cp2Ti(bdt). Similarly the structures of Cp2Ti(dsit) and Cp2Ti(Se2C2Z2) were also determined from single crystal X-ray diffraction. All complexes exhibit a strong folding of...
The magnetic properties of a series of three neutral radical organometallic complexes of general formula [CpNi(dithiolene)]. have been investigated by a combination of X-ray crystal structure analysis and magnetic susceptibility measurements, while the assignment of the exchange coupling constants to the possible exchange pathways has been accomplished with the help of calculations based on density functional theory (DFT). The syntheses and X-ray structures of [CpNi(adt)] (adt=acrylonitrile-2,3-dithiolate) and [CpNi(tfd)] (tfd=1,2-bis(trifluoromethyl)ethene-1,2-dithiolate) complexes are described, while [CpNi(mnt)] (mnt=maleonitriledithiolate) was reported earlier. In the three complexes, we observed strong antiferromagnetic coupling that could not be explained solely by short SS intermolecular contacts. Our calculations indicated that...
A novel paramagnetic (S = 1/2) copper dithiolene complex based on the tfadt ligand (tfadt: 3-trifluoromethyl-acrylonitrile-2,3-dithiolate) is prepared as its n-Bu4N+ salt and crystallized with [Ni(cyclam)]2+ into infinite, one-dimensional chains through CN***Ni interactions, avoiding any direct (antiferromagnetic) overlap between the dithiolene complexes. An unprecedented ferromagnetic interaction within the heterobimetallic chains between the S = 1/2 [Cu(tfadt)2]2− and the S = 1 [Ni(cyclam)]2+ tectons is observed, despite the fact that the SOMOs of both [Cu(tfadt)2]2− (with dx2−y2 symmetry) and [Ni(cyclam)]2+ (with dx2−y2 and dz2 symmetry) have the same eg symmetry. The experimental exchange interaction deduced from the fit of the magnetic susceptibility (Jexp/kB = +5.0 K) was confirmed by theoretical calculations (Jcalc/kB = +7.3 K),...
Want to know more?If you want to know more about this cutting edge product, or schedule a demonstration on your own organisation, please feel free to contact us or read the available documentation at http://www.keep.pt/produtos/retrievo/?lang=en