Bimetallamacrocycles involving tetrakis(diphenylphosphinoalkylthio)tetrathiafulvalene

Two novel tetrathiafulvalene (TTF) ligands, substituted by four diphenylphosphinoalkylthio groups, have been synthesized and characterized. Their redox properties, determined by cyclic voltammetry, have been compared with their precursors and discussed. The ability of these redox active ligands to react with two equivalent of cis-W(CO)₄(C₅H₁₁N)₂ is presented. X-ray crystal structure of a bis 13-metallamacrocycle is reported together with its redox behaviour.     

The first methyl antimony linked dimeric tetrathiafulvalene and tetraselenafulvalenes

In quest of novel organic donors, dimeric tetrathiafulvalene (TTF) and tetraselenafulvalenes (TSFs) linked by a single or double methyl antimony bridge, MeSb(TTF)₂ (1), (MeSb)₂(TSF)₂ (cis-2 and trans-2), and MeSb(TSF)₂ (3), have been synthesized. Singly bridged 1 and 3 show three pairs of redox waves, whereas doubly bridged cis-2 and trans-2 show two pairs of redox waves similarly to TSF. The X-ray structural analyses of neutral crystals, 1, cis-2 and trans-2, have succeeded. In their structures, antimony and chalcogen atoms form close intermolecular contacts useful in constructing supramolecular networks.     

3,4‐[2,2‐Bis(methoxyethoxymethoxymethyl)propylenedithio]‐3′,4′‐(ethylenedithio)tetrathiafulvalene: a spiro‐substituted BEDT–TTF analogue

The crystal structure of the title compound [systematic name: 2‐(1,3‐dithiolo[4,5‐b][1,4]dithiin‐2‐ylidene)‐6,6‐bis(methoxyethoxymethoxymethyl)‐1,3‐dithiolo[4,5‐b][1,4]dithiepine], C₂₁H₃₀O₆S₈, a spiro‐substituted BEDT–TTF analogue [BEDT–TTF is bis(ethylenedithio)tetrathiafulvalene], has a strongly bent heterocyclic framework. The seven‐membered ring adopts a pseudo‐chair conformation with notably widened ring bond angles, especially at the methylene C atoms [119.49 (11) and 117.60 (11)°]. The axial side chain adopts an extended conformation, but the equatorial side chain curls back on itself and the O atom nearest the ring system is involved in three short contacts to H atoms (2.45–2.53 Å). The molecules pack in centrosymmetrically related pairs, which are isolated from each other by columns of the polyether side chains. This study emphasizes the ease of distortion of the neutral bis(propylenedithio)tetrathiafulvalene ring structure, and how the need to accommodate side chains can easily override the tendency of these donor systems to form stacks in the crystalline state.     

Cis‐ and trans‐bis(2‐cyano­ethyl­sulfan­yl)(decane‐1,10‐diyldithio)tetra­thia­fulvalene

The isomeric title compounds, 2,7‐bis(2‐cyanoethylsulfanyl)‐3,6‐(decane‐1,10‐diyldithio)tetrathiafulvalene and 2,6‐bis­(2‐cyanoethylsulfanyl)‐3,7‐(decane‐1,10‐diyldithio)­tetra­thiafulvalene, both C₂₂H₂₈N₂S₈, comprise bis­(2‐cyano­ethyl­sulfan­yl)tetra­thia­fulvalene units tethered by a saturated deca­methyl­enedithio linker attached in either a cis or a trans manner. The tetra­thia­fulvalene (TTF) group is planar in the cis isomer, but distorted significantly from planarity and twisted about its long axis in the trans isomer. In both structures, inter­molecular inter­actions are segregated into regions in which TTF units are brought into close contact and regions where the polymethyl­ene chains are brought into close contact. In the cis isomer, TTF units exhibit π–π stacking inter­actions, while in the trans isomer they do not.     

Synthesis, structures, and conductivities of salts (BEDT-TTF)[9,9′(12′)-I2-3,3′-Co(1,2-C2B9H10)2] and (TTF)[9,9′,12,12′-I4-3,3′-Co(1,2-C2B9H9)2]

The radical cation salts of tetrathiafulvalene (TTF) and bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF) with iodo derivatives of cobalt bis(dicarbollide), (TTF)[9,9′,12,12′-I₄-3,3′-Co(1,2-C₂B₉H₉)₂] and (BEDT-TTF)[9,9′(12′)-I₂-3,3′-Co(1,2-C₂B₉H₁₀)₂], respectively, were synthesized and their crystal structures were determined. The introduction of iodine atoms into the lower rim of the dicarbollide ligands, unlike the substitution at the upper rim, leads to insignificant changes in the crystal structure and the conductivity of the radical cation salts compared to the analogous salts based on unsubstituted cobalt bis(dicarbollide).     

Mono‐ and Binuclear Dimethylthallium(III) Complexes with o‐Benzoquinone‐TTF‐o‐Benzoquinone Ligand; Synthesis,Spectroscopy and X‐ray Study

The new mono‐ and binuclear semiquinonato dimethylthallium complexes (Q‐TTF‐SQ)TlMe₂ ( 1 ) and Me₂Tl(SQ‐TTF‐SQ)TlMe₂ ( 2 ) based on di‐o‐quinone with tetrathiafulvalene (TTF) bridge, 4,4′,7,7′‐tetra‐tert‐butyl‐2,2′‐bis‐1,3‐benzodithiol‐5,5′,6,6′‐tetraone Q‐TTF‐Q, were synthesized by the reaction between corresponding mono‐ and di‐sodium semiquinonates (Q‐TTF‐SQ)Na and Na(SQ‐TTF‐SQ)Na and one or two equivalents of Me₂TlCl, respectively. The same products could be obtained by the interaction of Q‐TTF‐Q with one or two equivalents of Me₃Tl. Complexes 1 and 2 were characterized by IR and electronic absorption spectroscopy, EPR, and magnetic measurements. The molecular structures of 1 and 2 were determined by single‐crystal X‐ray diffraction. It was found that mono‐semiquinonato derivative 1 partially disproportionates into Q‐TTF‐Q and binuclear complex 2 in THF solution. According to variable temperature magnetic susceptibility measurements and EPR data, compound 1 reveals paramagnetic behavior with an S = 1/2 state in the range 50–300 K, whereas compound 2 has an S = 0 ground state as the consequence of antiferromagnetic coupling between semiquinonato moieties realized through the TTF‐bridge.     

Bimetallic neutral palladium (II) bis(dithiolene) complex: Unusual synthesis,structural and theoretical study

The unusual synthesis of the dimeric dithiolene complex [(PPh₃)Pd(ethylene-1,2-dithiolate)]₂ (1), containing the simplest dithiolene ligand, has been achieved through the reaction between tetrathiafulvalene (TTF) and Pd(PPh₃)₄. The complex shows a folded structure in the solid state, according to single crystal X-ray analysis performed on crystals grown from two different system solvents and conditions, with a central [Pd₂S₂] ring folded about the S···S hinge by 67.9°. The optimized geometry at the DFT level is in excellent agreement with the experimental structure. Moreover, TD-DFT calculations allowed the assignment of the low energy band arising at 576 nm to the HOMO→LUMO transition, between frontier orbitals having mixed metal and dithiolene character.     

Chiral, flexible binaphthol-substituted tetrathiafulvalenes

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)(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 binaphthol moieties adopt a cisoid conformation with a dihedral angle between naphthyl rings in the range 80-85°. The racemic EDT/TTF derivative allowed for the isolation of two crystalline charge-transfer compounds with the electron acceptors TCNQ and TCNQF₄. The donor and acceptor molecules are organized into homo-dyads in the TCNQ neutral complex, insulating and diamagnetic. On the other hand, a full charge transfer occurs in the TCNQF₄ salt, with weakly interacting chiral TTF cation and TCNQF₄ anion radicals.     

Donor–acceptor complex of a new bis‐TTF donor containing a pyridine diester spacer with TCNQ as the acceptor: a disappointing system

A new bis‐TTF donor (TTF is tetrathiafulvalene) containing a pyridine diester spacer, namely bis{2‐[(6,7‐tetramethylene‐3‐methylsulfanyltetrathiafulvalen‐2‐yl)sulfanyl]ethyl} pyridine‐2,6‐dicarboxylate–tetracyanoquinodimethane–dichloromethane (2/1/2), 2C₃₃H₃₃NO₄S₁₂·C₁₂H₄N₄·2CH₂Cl₂, has been synthesized and its electron‐donating ability determined by cyclic voltammetry. The electrical conductivity and crystal structure of this donor–acceptor (DA) complex with TCNQ (tetracyanoquinodimethane) as the acceptor are presented. The TCNQ moiety lies across a crystallographic inversion centre. In the crystal structure, TTF and TCNQ entities are arranged in alternate stacks; this feature, together with the bond lengths of the TCNQ molecule, suggest that the expected charge transfer has not occurred and that the D and A entities are in the neutral state, in agreement with the poor conductivity of the material (σ_RT = 2 × 10⁻⁶ S cm⁻¹).     

Covalent association of polyaza macrocyclic units to the electroactive tetrathiafulvalene moiety: synthesis and structural analysis

The synthesis of new macrocyclic receptors associating the electroactive tetrathiafulvalene unit (TTF) to different polyaza ligands is described. The structure of these receptors varies by the size of the coordinating unit (polyaza chains of various lengths), and by the nature of the latter, since a macrocyclic cyclam or a diazatetraoxa macrocycle derivative has been also introduced. The X-ray diffraction study on a single crystal of one of these receptors, demonstrates the electroactive TTF framework to be planar enough to present the expected reversible electrochemical behaviour. A preliminary study of the coordination ability of these polyazaTTF receptors is also given. To cite this article: G. Trippé et al., C. R. Chimie 6 (2003).     

Metal complexes of mercaptoamines—II: New assignment of the structure of bis(β-mercaptoethylamine)nickel(II) and related compounds

A cis-geometry was proposed for the green complex bis(β-mercaptoethylamine) nickel(II) on the basis of its reactivity, IR spectroscopy and orbital geometry considerations. The crystal and molecular structure of this complex has been determined by X-ray diffraction and shows that the complex has a trans geometry. The crystal structure consists of trans-NiL₂ molecules strongly linked through NH-S hydrogen bonds. Electronic and IR spectroscopy, and powder X-ray analysis are in agreement with the same trans geometry for the complexes bis(β-mercaptoethylamine)palladium(II) and bis-(γ-mercaptopropylamine)nickel(II). As a result of the new assignment of the structure of these complexes some concepts, such as its reactivity with nickel(II), are reconsidered.     

Structure of polypiperylene chain segments according to high-resolution 13C NMR spectra

The microstructure of stereoregular 1,4-trans-and 1,4-cis-polypiperylenes, as well as polymers prepared from the trans-and cis-piperylene isomers via cationic polymerization in the presence of TiCl₄, was studied by high-resolution ¹³C NMR spectroscopy. Polypiperylene synthesized through the cationic polymerization of the cis isomer had a more diversified morphology of the macromolecular chain, i.e., had higher relative amounts of 1,2-cis-units and combinations of irregular-addition 1,4-trans-units. It was shown that ¹³C NMR spectra give the most comprehensive and independent information on the details of structure of the piperylene macromolecular chain.     

Synthesis and reactions of a monosubstituted dithiirane 1-oxide, 3-(9-triptycyl)dithiirane 1-oxide

A 3-monosubstituted dithiirane 1-oxide, 3-(9-triptycyl)dithiirane 1-oxide, was prepared for the first time, by the reaction of (9-triptycyl)diazomethane and S₈O. The dithiirane 1-oxide was obtained as cis- and trans-isomers, and the structure of the trans-isomer was verified by X-ray crystallography. The cis-isomer isomerized gradually to the trans-isomer in solution. The divalent sulfur atom of the cis- and trans-dithiirane 1-oxides were removed on treatment with triphenylphosphine to give the corresponding Z- and E-sulfines, respectively. The reaction of the trans-dithiirane 1-oxide with (Ph₃P)₂Pt(C₂H₄) provided the (sulfenato-thiolato)Pt^II complex, and that with Lawesson's reagent yielded the 1,3,4,2-trithiaphospholane and 1,2,4,5,3-tetrathiaphosphorinane derivatives.     

PhP-PPh group bound to 1,8-positions of naphthalene: Preparation of cis isomer and synthesis of binuclear complex

A thermodynamically less stable cis isomer of 1,2-diphosphacycle was prepared from the corresponding trans isomer. Diphosphine, in which a PhP-PPh bond bridges the 1,8-positions of naphthalene, 1,2-diphenyl-1,2-dihydronaphtho[1,8-cd][1,2]diphosphole (1), was first prepared according to a previously reported method, and the trans isomer of 1 was irradiated in tetrahydrofuran with UV-vis light to reach equilibrium with cis-1 in a trans:cis ratio of 1:2. When a similar photochemical conversion was carried out using a saturated hexane solution of trans-1, cis-1 was precipitated in a good yield of 94%. The configuration of cis-1 was confirmed by X-ray analysis. Both cis- and trans-1 diphosphine ligands were used for the preparation of binuclear gold complexes. The crystal structure of (μ-cis-1)-[AuCl]₂ demonstrated that the two lone pairs of cis-1 are suitably directed for arrangement of the two gold centers in close proximity to each other. The two independent (μ-cis-1)-[AuCl]₂ molecules in the crystal were found to form a dimer through the multiple intermolecular interaction among the gold centers.     

Schwefel(IV)-Verbindungen als Liganden XII. Ringöffnung von Thiiran-1-oxid,Struktur des intermediären Lewis-Säure-Addukts

Thiirane-1-oxide forms a 2:1 adduct with bis(4-fluorophenyl)tin dichloride, the structure of which has been determined by X-ray crystallography. The molecule is octahedral with a trans aryl, cis dichloro, cis sulfoxide arrangement. In the adduct the SO bond is longer than in the free sulfoxide while the bonds within the three-membered ring are shorter. Nucleophilic attack on carbon by Cl⁻ or Br⁻ gives rise to ring opening and formation of thiosulfinic acid esters XC₂H₄S(O)SC₂H₄X.     

Hydrogen bonding networks and proton transfer compounds of cobalt(II) and copper(II) with pyridine-2,5-dicarboxylate

Three Co(II) and Cu(II)-pyridine-2,5-dicarboxylate (pydc) proton transfer compounds with 1,4-butanediamine (ben) and 2,2-dimethylpropane-1,3-diamine (dmpen), trans-(H₂ben)[Co(pydc)₂(H₂O)₂]·4H₂O (1), trans-(H₂dmpen)[Co(pydc)₂(H₂O)₂]·2H₂O (2) and (H₂ben)₂[Cu₂(μ-pydc)₄(H₂O)₂] (3) have been synthesized and characterized by the methods of elemental, spectroscopic (IR and UV-Vis), thermal (TG/DTG, DTA) analysis, magnetic measurement and single crystal X-ray diffraction. The crystallographic analysis revealed that the complexes consist of [Co(pydc)₂(H₂O)₂]²⁻ anion, bis(protonated) diamine cation (H₂ben for 1 and H₂dmpen for 2) and four and two crystal water molecules, respectively. The Co(II) ions are coordinated by two pydc and two aqua ligands. The bis(deprotonated) pydc ligands coordinate to the Co(II) ions through the nitrogen atom of pyridine ring and the oxygen atom of carboxylate group, creating a chelate ring. The distorted octahedral geometries are completed by two trans aqua ligands at axial positions. The molecular structure of the complex 3 consists of dinuclear [Cu₂(μ-pydc)₄(H₂O)₂]⁴⁻ units and bis(protonated) 1,4-butanediammonium cation. In the structure, each Cu(II) ion is coordinated by two nitrogen and two oxygen atoms from two pydc ligands and one oxygen atom from aqua ligand, forming a distorted square pyramidal geometry.     

First separation and characterization of cis and trans 1,2-bisaryloxy perfluorocyclobutanes

4-Bromotrifluorovinyloxybenzene (4-Br-TFVE) undergoes cyclodimerization upon heating at 150 °C affording cis and trans isomers of 1,2-bis(4-bromophenoxy)hexafluorocylcobutane. Stereoisomers were separated by selective crystallization, confirmed by single crystal X-ray, and further characterized by NMR. Remarkable difference in the solid state structures include aryl to aryl dihedral angles of 12° for the trans isomer and 88° for the cis isomer. Polymers containing roughly equal amounts of cis and trans fused perfluorocyclobutyl (PFCB) rings should be expected to have low crystallinity due to the marked difference in the two unit cells as is observed.     

Synthesis, structure, photochromism and DFT calculations of copper(I)-triphenylphosphine halide complexes of thioalkylazoimidazoles

[Cu(SRaaiNR′)(PPh₃)X] complexes are synthesized by the reaction of CuX (X = Cl, Br, I), triphenylphosphine and 1-alkyl-2-[(o-thioalkyl)phenylazo]imidazole (SRaaiNR′). The single crystal X-ray structure of [Cu(SEtaaiNH)(PPh₃)I] (SEtaaiNH = 2-[(o-thioethyl)phenylazo]imidazole) shows a distorted tetrahedral geometry of the copper center with bidentate, N(azo), N(imidazole) chelation of SEtaaiNH and coordination from PPh₃ and iodine. These complexes show a trans-to-cis isomerization upon irradiation with UV light. The reverse transformation, cis-to-trans isomerization, is very slow with visible light irradiation and is thermally accessible. The quantum yields (?_t→c) of the trans-to-cis isomerization of [Cu(SRaaiNR′)(PPh₃)X] are lower than the free ligand values. This is due to the increased mass and rotor volume of the complexes compared to the free ligand data. The rate of isomerization follows the order: [Cu(SRaaiNR′)(PPh₃)Cl] < [Cu(SRaaiNR′)(PPh₃)Br] < [Cu(SRaaiNR′)(PPh₃)I]. The activation energy (E_a) of the cis-to-trans isomerization is calculated by a controlled temperature reaction. DFT computation of representative complexes has been used to determine the composition and energy of the molecular levels.     

From oxides of internal perfluoroolefins to fluorocontaining camphor thiazolinylhydrazones

The reaction of oxides of internal trans- and cis-perfluoroolefins with (1S, 4S)- or racemic camphor thiosemicarbazone leads to the formation of trans- and cis-isomers of (1S, 4S)- or racemic camphor 5′-fluoro-4′-hydroxy-4′,5′-di(perfluoroalkyl)-1′,3′-thiazolinyl-2′-hydrazones, respectively. Unsymmetrical dodecafluoro-2,3-epoxyhexane yields a mixture of regioisomeric hydrazones. The molecular structure of the trans-isomer of (1S, 4S)-camphor 5′-fluoro-4′-hydroxy-4′,5′-bis(trifluoromethyl)-1′,3′-thiazolinyl-2′-hydrazone has been established by X-ray crystallography. The quite rare example of cocrystallization of two diastereomers of the latter in homochiral crystal (sp. group P2₁) has been revealed.     

Synthesis and characterization of a new family of spin bearing TTF ligands

The syntheses and characterization of two new tetrathiafulvalene (TTF) derivatives bearing pyridine-based substituents and 1,5'-dimethyl-6-oxoverdazyl radicals are described. The TTF-pyridine and bipyridine aldehydes were prepared via a palladium-catalyzed cross-coupling reaction between mono(tributylstannyl)tetrathiafulvalene (3) and the appropriate formylpyridyl halides (4). The radical precursors, the corresponding 1,2,4,5-tetrazanes, were prepared by condensation of the bis(1-methylhydrazide) of carbonic acid with the TTF bearing pyridyl aldehyde. Oxidation of tetrazanes 8 and 9 with 1,4-benzoquinone afforded the donor radicals 1 and 2 as 1:1 complexes with hydroquinone. Both complexes are stable in the solid state and their electronic properties have been characterized by EPR, cyclic voltammetry, and UV/vis spectroscopy. The TTF core of both compounds was oxidized both chemically and electrochemically to afford the corresponding cation diradical species. The electronic properties of both donor radicals have been probed by cyclic voltammetry, UV-vis spectroscopy, and preliminary EPR measurements.