Synthesis of bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF) derivatives functionalised with two, four or eight hydroxyl groups

Short synthetic routes to a range of BEDT-TTF derivatives functionalised with two, four or eight hydroxyl groups are reported, of interest because of their potential for introducing hydrogen bonding between donor and anion into their radical cation salts. The cycloaddition of 1,3-dithiole-2,4,5-trithione with alkenes to construct 5,6-dihydro-1,3-dithiolo[4,5-b]1,4-dithiin-2-thiones is a key step, with homo- or hetero-coupling procedures and O-deprotection completing the syntheses. The first synthesis of a single diastereomer of tetrakis(hydroxymethyl)BEDT-TTF, the cis,trans product, was achieved by careful choice of O-protecting groups to facilitate separation of homo- and hetero-coupled products. Cyclisation of the trithione with enantiopure 1R,2R,5R,6R-bis(O,O-isopropylidene)hex-3-ene-1,2,5,6-tetrol (from D-mannitol) gave two separable diastereomeric thiones, which can be transformed to enantiomeric BEDT-TTF derivatives with four or eight hydroxyl groups.     

Synthesis of bis(ethylenedithio)tetrathiafulvalene derivatives with metal ion ligating centres

The syntheses of eight derivatives of BEDT-TTF (ET) containing pyridine, 2,2′-bipyridine or 2,4′-pyridylpyrimidine binding sites on a side chain are reported, for use in the preparation of organic/inorganic hybrid materials. The intermediate hydroxyethyl derivative of BEDT-TTF is prepared in an efficient five-step procedure.     

Chemo- and enantioselective sulfoxidation of bis(ethylenedithio)-tetrathiafulvalene (BEDT-TTF) into chiral BEDT-TTF-sulfoxide

Selective sulfoxidation of BEDT-TTF (bis(ethylenedithio)-tetrathiafulvalene) with enantiopure (camphoryl-sulfonyl)oxaziridine derivatives provided the inner monosulfoxide, as demonstrated using single crystal X-ray analysis, with an enantiomeric excess of 44% (up to 74% after recrystallization).     

Synthesis, crystal structure, and physical properties of (BEDT-TTF)[Ni(tdas)2] (BEDT-TTF = bis(ethylenedithio)tetrathiafulvalene; tdas = 1,2,5-thiadiazole-3,4-dithiolate): first monomeric [Ni(tdas)2]- monoanion

We report the synthesis, structure, and physical properties of (BEDT-TTF)[Ni(tdas)2] [BEDT-TTF, or ET, is bis(ethylenedithio)tetrathiafulvalene; tdas is 1,2,5-thiadiazole-3,4-dithiolate], which is the first example of a salt containing monomeric [Ni(tdas)2]- monoanions. This salt, which crystallizes in the monoclinic space group P2(1)/c with a = 17.2324(6) A, b = 13.2740(5) A, c = 10.9467(4) A, beta = 96.974(2) degrees, and V = 2485.5(2) A(3), forms a layered structure. One layer contains dimerized BEDT-TTF electron donor molecules and isolated [Ni(tdas)2]- monoanions, while the second layer contains chains of [Ni(tdas)2]- monoanions. Conductivity measurements show that (BEDT-TTF)[Ni(tdas)2] has a semiconductor-to-semiconductor transition near 200 K, while magnetic measurements indicate that it is an S = 1/2 paramagnet with weak antiferromagnetic coupling. Reflectance spectra reveal bands in the near-infrared region (6.6 x 10(3) and 10.6 x 10(3) cm(-1)) which are typical of (BEDT-TTF)2(2+) dimers. From these data, we can conclude that the unpaired electron lies on the [Ni(tdas)2]- anions. Tight-binding band structure calculations were used to analyze the electronic structure of this salt.     

Novel bis(ethylenedithio)tetrathiafulvalene-based organic conductor with 1,1'-ferrocenedisulfonate

A new bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF)-based salt with a ferrocenyl moiety, alpha' '-(BEDT-TTF)(4)(Fe(C(5)H(4)SO(3))(2)).6H(2)O, has been prepared. The ferrocenyl part of this salt is neutral and diamagnetic, but the magnetic susceptibility is well modeled by a Curie-Weiss law with C = 0.142 emu.K.mol(-1) (approximately 1/3 of s = 1/2 spin). The spin is likely to be localized on the donor layer because of its unique charge disproportionation.     

Synthesis of highly functionalized 2(1H)-pyrazinone 3-carboxamide scaffolds

Synthesis of highly functionalized 2(1H)-pyrazinone 3-carboxamide derivatives is reported. A one-pot, two-step process including the base-mediated reaction of N,N-disubstituted aminoacetonitrile derivatives 18 with 3,5-dihalo-2(1H)-pyrazinones 1 afforded substituted aminoacetonitrile pyrazinone derivative 19, which on subsequent oxidation followed by transamidation of the resulting intermediate with primary or secondary amines gave the corresponding highly functionalized 2(1H)-pyrazinone 3-carboxamide derivatives 21.     

Generation and trapping of tricyclo[3.3.0.0]oct-1(5)-ene derivatives containing carbonyl functionalities

Two new functionalized highly pyramidalized tricyclo[3.3.0.0^3,7]oct-1(5)-ene derivatives containing carbonyl functionalities have been trapped as Diels-Alder adducts, although they failed to dimerize. An interesting fragmentation of the bisnoradamantane skeleton to norbornane derivatives has also been observed.     

New BEDT-TTF/[Fe(C5O5)3]3- hybrid system: synthesis, crystal structure, and physical properties of a chirality-induced alpha phase and a novel magnetic molecular metal

The paramagnetic and chiral anion [Fe(C5O5)3]3- (C5O52-=croconate) has been combined with the organic donor BEDT-TTF (=ET=bis(ethylenedithio)tetrathiafulvalene) to synthesize a novel paramagnetic semiconductor with the first chirality-induced alpha phase, alpha-(BEDT-TTF)5[Fe(C5O5)3].5H2O (1), and one of the few known paramagnetic molecular metals, beta-(BEDT-TTF)5[Fe(C5O5)3].C6H5CN (2). Both compounds present layers of BEDT-TTF molecules, with the alpha or beta packing modes, alternating with layers containing the high-spin S=5/2 Fe(III) anions and solvent molecules. In the alpha phase, the alternation of the chiral [Fe(C5O5)3]3- anions along the direction perpendicular to the BEDT-TTF chains induces an alternation of the tilt angle of the BEDT-TTF molecules, giving rise to the observed alpha phase. The alpha phase presents a semiconductor behavior with a high room-temperature conductivity (6 S.cm-1) and an activation energy of 116 meV. The beta phase presents a metallic behavior down to ca. 120 K, where a charge localization takes place with a reentrance to the metallic state below ca. 20 K followed by a metal-semiconductor transition at ca. 10 K. The magnetic properties are dominated by the paramagnetic S=5/2 [Fe(C5O5)3]3- anion with an extra Pauli-type paramagnetism in the metallic beta phase. The ESR spectra confirm the presence of the high-spin Fe(III)-containing anion and show a progressive localization in the organic sublattice along with an antiferromagnetic coupling below ca. 120 K that, in the metallic beta phase, could be at the origin of the transition from the metallic to the activated conductivity regime. The correlation between crystal structure and conductivity behavior has been studied by means of tight-binding band structure calculations which provide a rationalization of the charge distribution and conductivity results.     

Crystal chemistry and physical properties of superconducting and semiconducting charge transfer salts of the type (BEDT-TTF)(4)[A(I)M(III)(C2O4)3]*PhCN (A(I) = H30,NH4,K; M(III) = Cr, Fe, Co, Al; BEDT-TTF = bis(ethylenedithio)tetrathiafulvalene

Synthesis, structure determination by single-crystal X-ray diffraction, and physical properties are reported and compared for superconducting and semiconducting molecular charge-transfer salts with stoichiometry (BEDT-TTF)(4)[A(I)M(III)(C(2)O(4))(3)].PhCN, where A(I) = H(3)O, NH(4), K; M(III) = Cr, Fe, Co, Al; BEDT-TTF = bis(ethylenedithio) tetrathiafulvalene. Attempts to substitute M(III) with Ti, Ru, Rh, or Gd are also described. New compounds with M = Co and Al are prepared and detailed structural comparisons are made across the whole series. Compounds with A = H(3)O(+) and M = Cr, Fe are monoclinic (space group C2/c), at 150, 120 K a = 10.240(1) A, 10.232(12) A; b = 19.965(1) A, 20.04(3) A; c = 34.905(1) A, 34.97(2) A; beta = 93.69(1) degrees, 93.25(11) degrees, respectively, both with Z = 4. These salts are metallic at room temperature, becoming superconducting at 5.5(5) or 8.5(5) K, respectively. A polymorph with A = H(3)O(+) and M = Cr is orthorhombic (Pbcn) with a = 10.371(2) A, b = 19.518(3) A, c = 35.646(3) A, and Z = 4 at 150 K. When A = NH(4)(+), M = Fe, Co, Al, the compounds are also orthorhombic (Pbcn), with a = 10.370(5) A, 10.340(1) A, 10.318(7) A; b = 19.588(12) A, 19.502(1) A, 19.460(4) A; c = 35.790(8) A, 35.768(1) A, 35.808(8) A at 150 K, respectively, with Z = 4. All of the Pbcn phases are semiconducting with activation energies between 0.15 and 0.22 eV. For those compounds which are thought to contain H(3)O(+), Raman spectroscopy or C=C and C-S bond lengths of the BEDT-TTF molecules confirm the presence of H(3)O(+) rather than H(2)O. In the monoclinic compounds the BEDT-TTF molecules adopt a beta' ' packing motif while in the orthorhombic phases (BEDT-TTF)(2) dimers are surrounded by monomers. Raman spectra and bond length analysis for the latter confirm that each molecule of the dimer has a charge of +1 while the remaining donors are neutral. All of the compounds contain approximately hexagonal honeycomb layers of [AM(C(2)O(4))(3)] and PhCN, with the solvent occupying a cavity bounded by [M(C(2)O(4))(3)](3-) and A. In the monoclinic series each layer contains one enantiomeric conformation of the chiral [M(C(2)O(4))(3)](3-) anions with alternate layers having opposite chirality, whereas in the orthorhombic series the enantiomers form chains within each layer. Analysis of the supramolecular organization at the interface between the cation and anion layers shows that this difference is responsible for the two different BEDT-TTF packing motifs, as a consequence of weak H-bonding interactions between the terminal ethylene groups in the donor and the [M(C(2)O(4))(3)](3-) oxygen atoms.     

A new radical cation salt bis(ethylenedithio)tetrathiafulvalene with [Pt(NO2)4]2− anion: Synthesis, structure, and conductivity

A radical cation salt based on bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF) containing the [Pt(NO₂)₄]^2? anion was synthesized for the first time. The crystal and molecular structure of this salt, (BEDT-TTF)₂Pt(NO₂)₄, was established by X-ray diffraction analysis. The crystal structure consists of radical cation BEDT-TTF layers between which planar-square anions [Pt(NO₂)₄]^2? are located. The layers are formed by BEDT-TTF stacks built of dimers. The interplanar distances within the dimers and between them are 3.41 and 3.96 Å, respectively. The distribution of the bond lengths and bond angles in BEDT-TTF corresponds to the charge of the cation +1. The room-temperature conductivity of (BEDT-TTF)₂Pt(NO₂)₄ is 3·10^?3 Ω^?1 cm^?1, and the temperature dependence of the conductivity exhibits the semiconducting character.     

A chirality-induced alpha phase and a novel molecular magnetic metal in the BEDT-TTF/tris(croconate)ferrate(III) hybrid molecular system

The novel paramagnetic and chiral anion [Fe(C5O5)3]3- has been combined with the organic donor BEDT-TTF (= ET = bis(ethylenedithio)tetrathiafulvalene) to yield the first chirality-induced alpha phase and a paramagnetic metal.     

An in-depth correlation of perturbation of the organic-inorganic interface topology,electronic structure,and transport properties within beta''-(BEDT-TTF)(4) x (guest)(n) x [Re(6)Q(6)Cl(8)], (Q=S,Se)

An in-depth analysis of a set of 21 layered structures of metallic pseudopolymorphs of general formulation, beta'-(BEDT-TTF)(4) x (guest)(n) x [Re(6)Q(6)Cl(8)], (BEDT-TTF=bis-ethylenedithiotetrathiafulvalene; Q = S, Se; guest = H(2)O, 1,4-dioxane, THF, CCl(4), C(2)H(5)OH, CHCl(3), CH(2)ClI, CH(2)ClBr, CH(2)Cl(2), CH(2)OH-CH(2)OH, C(5)H(5)N, CH(3)COCH(3), 2-hydroxy-tetrahydrofuran, CH(3)CN, CS(2), C(6)H(6)), with diverse low-temperature behaviors, which differ solely by the nature of the cosolvent molecule selectively included during the electrocrystallization process, reveals a precise set of weak HO-H...Cl-mu-Re, (C-H)(BEDT-TTF)...Cl-mu-Re, C-H...O(guest), (C-H)(guest)...Cl-mu-Re hydrogen bonds at the organic-inorganic interface, none of which dominates any of the others and whose balance is adjusted upon substitution of one guest molecule by another. The electronic structure of the host adjusts to the weak perturbation imposed by exchanging the guest molecules and by balancing the former interfacial interactions; this correlates to a net activation of up to 0.1 eV of the energy of the HOMO level of one of the two donors, while keeping the pattern of HOMO-HOMO intermolecular interactions in the donor layer essentially unaltered. It is suggested that this controls the stability of the metallic state at low temperature or the occurrence of a metal-to-insulator phase transition for particular guests along the series. It is concluded that by allowing for numerous tiny modifications at the organic-inorganic interface within a single, robust host structure, one sees a concerted, inherently weak structural response of the system that is proportional to the magnitude of the underlying, equally weak activation of the HOMO energy of a fraction of the pi-donor molecules within the slabs; this has a sizeable influence on the macroscopic transport properties of the system.     

A New Approach to the Asymmetric Reaction of the Chiron 5－L－Menthyloxy－2（5H）－furanones with Horner－Emmons Reagent

The asymmetric reaction of the chiron 2(5H )-furanones (4a-4c) with the Horner-Emmons reagents (5a-5b) has been investigated. The newly chirai organophosphorus derivatives 6 and 7 were obtained using the phosphoryl-stabilized carbanion as a building block in DMSO under mild conditions. Through the asymmetric introduction, the Horner-Emmons reagent could be transformed to a chiral building block to afford the novel functionalized phosphorus derivatives. The structures of the synthesized compounds 6 and 7 were identified on the basis of their elementary and spectroscopic data, such as IR,^1H NMR, ^13C NMR, MS and X-ray crystallography. These resuits provided a valuable approach to the synthesis of potentially interesting chirai organophosphorus derivatives and probing their biological activities.     

Crystal and molecular structure of (BEDT-TTF)4Cd2I6

The new radical-cation salt (BEDT-TTF)₄Cd₂I₆ has been studied by x-ray diffraction (a=19.284(6), b=12.84(1), c=7.869 (2) Å; α=72.77(4), β=94.44(2), γ= 103.97(3)^o, space group P1, Z=1, d_calc=2.32 g/cm³). The radical cation (BEDT-TTF)^1/2+ and the Cd₂I₆ ^2? anions form organic and inorganic layers alternating along the a axis. In the organic layer, (BEDT-TTF)^1/2+ are arranged in stacks and ribbons. The radical-cations in the ribbon are packed “side to side” and are joined to one another through shortened intermolecular contacts S...S 3.346(5)-3.657(4) Å. The Cd₂I₆ ^2? anion is dimeric. The Cd atom has a distorted tetrahedral bond configuration, with bond lengths Cd-I 2.722(l)-2.886(1) Å and valence angles I-Cd-I 93.8(1)-114.1(1)°.     

Enantioselective nitrone cycloadditions of alpha,beta-unsaturated 2-acyl imidazoles catalyzed by bis(oxazolinyl)pyridine-cerium(IV) triflate complexes

[Structure: see text] Enantioselective nitrone cycloadditions with beta-substituted alpha,beta-unsaturated 2-acyl imidazoles catalyzed by bis(oxazolinyl)pyridine-cerium(IV) triflate complexes 1 have been reported. The isoxazolidine products were efficiently transformed into densely functionalized beta'-hydroxy-beta-amino acid derivatives.     

Structure of (BEDT-TTF)-Based Organic Metals with Photochromic Nitroprusside Anion (BEDT-TTF)4M[FeNO(CN)5]2, where M = Na+, K+, NH+4, Tl+, Rb+, and Cs+

The crystal and molecular structures of a family of three-component radical cation salts bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF), (BEDT-TTF)₄M[NP]₂, where M = Na⁺, K⁺, NH⁺ ₄, Tl⁺, Rb⁺, and Cs⁺and NP is the nitroprusside anion [FeNO(CN)₅]^2–, are studied by X-ray structure analysis. These salts are isostructural and behave as stable metals down to helium temperatures. Their structures are characterized by radical cation layers of the "-type alternating with layers of complex anions [M⁺(NP^2–)₂]^3–. The conducting radical cation system and photochromic nitroprusside anion in the crystals were shown to affect each other. On the one hand, this changes the geometric parameters of the nitroprusside anion as compared to those of the Na₂[NP] · 2H₂O crystals in the ground state and, on the other hand, makes the geometries of the two crystallographically independent BEDT-TTF molecules with a different number of shortened contacts with the anion different. Based on the data of crystallochemical analysis of the (BEDT-TTF)₄M[FeNO(CN)₅]₂structures, we suggest their possible routes of chemical modification with the purpose of changing their physical properties.     

Arbuzov chemistry with chlorofullerene C(60)Cl(6): a powerful method for selective synthesis of highly functionalized [60]fullerene derivatives

We report Arbuzov-type reactions of chlorofullerene C(60)Cl(6) with trialkyl phosphites producing highly functionalized fullerene derivatives C(60)[P(O)(OR)(2)](5)H with high yields. The designed family of [60]fullerene phosphonic acids and their esters showed unusual properties which might find valuable material science applications.     

Novel synthesis of 7-fluoro-8-(trifluoromethyl)- 1H-1,6-naphthyridin-4-one derivatives: intermolecular cyclization of an N-silyl-1-azaallyl anion with perfluoroalkene and subsequent intramolecular skeletal transformation of the resulting pentasubstituted pyridines

In this study, fluorine-containing pentasubstituted pyridine derivatives 9a-m were prepared regioselectively in good yields by the intermolecular cyclization of a variety of N-silyl-1-azaallylic anion intermediates 7, which were generated from a functionalized silane 5 and an aromatic/aliphatic nitrile 6 with perfluoroalkene 8. Also, 7-fluoro-8-(trifluoromethyl)-1H-1,6-naphthyridin-4-one derivatives 11a-k were synthesized in excellent yields by the subsequent base-promoted intramolecular skeletal transformation of the resulting pyridine derivatives 10a-k.     

Pentakis(trifluoromethyl)phenyl, a sterically crowded and electron-withdrawing group: synthesis and acidity of pentakis(trifluoromethyl)benzene, -toluene, -phenol, and -aniline

A general route to functionalized pentakis(trifluoromethyl)phenyl (C6(CF3)5) derivatives, promising building blocks for designing novel stable carbenes, radical species, superacids, weakly coordinating anions and other practically and theoretically useful species, is presented. This pertrifluoromethylation route proceeds via conveniently pregenerated (trifluoromethyl)copper (CF3Cu) species in DMF, stabilized by addition of 1,3-dimethyl-2-imidazolidinone (DMI). These species react with hexaiodobenzene at ambient temperature to give the potassium pentakis(trifluoromethyl)phenoxide along with hexakis(trifluoromethyl)benzene and pentakis(trifluoromethyl)benzene in a combined yield of 80%. A possible reaction pathway explaining the formation of pentakis(trifluoromethyl)phenoxide is proposed. Pentakis(trifluoromethyl)phenol gives rise to easily functionalized pentakis(trifluoromethyl)chlorobenzene and pentakis(trifluoromethyl)aniline. Pertrifluoromethylation of pentaiodochlorobenzene and pentaiodotoluene allows straightforward access to pentakis(trifluoromethyl)chlorobenzene and pentakis(trifluoromethyl)toluene, respectively. XRD structures of several C6(CF3)5 derivatives were determined and compared with the calculated structures. Due to the steric crowding the aromatic rings in all C6(CF3)5 derivatives are significantly distorted. The gas-phase acidities (Delta Gacid) and pKa values in different solvents (acetonitrile (AN), DMSO, water) for the title compounds and a number of related compounds have been measured. The origin of the acidifying effect of the C6(CF3)5 group has been explored using the isodesmic reactions approach.     

A new class of arylpiperazine derivatives: the library synthesis on SynPhase lanterns and biological evaluation on serotonin 5-HT(1A) and 5-HT(2A) receptors

An efficient solid-supported method for the synthesis of a new class of arylpiperazine derivatives containing amino acid residues has been developed. A 72-membered library was synthesized on SynPhase Lanterns functionalized by a BAL linker. A one-pot cleavage/cyclization step of aspartic and glutamic acid derivatives yielded succinimide- and pyroglutamyl-containing ligands (chemsets 9 and 10). The library representatives under study showed different levels of affinity for 5-HT(1A) and 5-HT(2A) receptors (estimated K(i) = 24-4000 and 1-2130 nM, respectively). Several dual 5-HT(1A)/5-HT(2A) ligands were found, of which two (9(3,3) and 9(3,5)) displayed high 5-HT(2A) affinity comparable to that of the reference drug ritanserin. A set of individual fragment contributions for the prediction of 5-HT(1A) and 5-HT(2A) affinity of all the library members were defined on the basis of the Free-Wilson analysis of 26 compounds. An alkylarylpiperazine fragment had essentially the same impact on the affinity for both receptors, whereas different terminal amide fragments were preferred by 5-HT(1A) (chemset 17, R(2) = adamantyl) and 5-HT(2A) (chemset 9, R(2) = norborn-2-ylmethyl) binding sites.