Structural and vibrational studies of molecular conductors using quantum mechanical methods: 1,3-Dithiole-2-thione, 1,3-dithiole-2-one, 1,3-dioxole-2-one and 1,3-dioxole-2-thione

Computations were carried out by employing the RHF and density functional theory (DFT) methods to investigate the geometries, atomic charges, harmonic vibrational frequencies for the 1,3-dithiole-2-thione (DTT), 1,3-dithiole-2-one (DTO), 1,3-dioxole-2-thione (DOT) and 1,3-dioxole-2-one (DOO) molecules and their radical cations. The geometrical parameters and atomic charges on various atomic sites of the DTT and DOT molecules and their radical cations suggest extended conjugation in these systems. Contrary to this, for the DOO⁺ and DTO⁺ ions there is no evidence in favour of such conjugation, however, the neutral molecules exhibit some conjugation. Harmonic forced field and vibrational mode calculations provided convincing theoretical evidence for the reassignment of some fundamental vibrational modes for all the four molecules. In going from the neutral species to the charged ions for all the four cases the CC stretching frequency is found to decrease drastically. The CS stretching frequency reduces drastically for the DTT and DOT molecules as compared to their radical cations whereas the CO stretching frequency is found to increase in going from the neutral molecule to its radical cation for the DOO and DTO molecules. The ring stretching mode with a₁ symmetry and CC and CO/S stretching modes in these molecules appear to help in conversion of neutral molecule into respective radical cation and neighbouring radical cation into respective neutral molecule. Thus, there appears the feasibility of stretching vibrational mode coupling with electron transfer.     

Photochromic dihetarylethenes. 17. Synthesis and photochromic properties of dithienylethenes containing new heterocyclic bridging fragments

Procedures were developed for the synthesis of substituted bis(2,5-dimethyl-3-thienyl)ethenes containing the imidazol-2-one, 1,3-dioxol-2-one, or 1,3-oxazol-2-one fragments as ethene bridges. These compounds were demonstrated to exhibit the photochromic properties. The cyclic forms of some imidazolone and oxazolone photochromes possess high thermal stability. The structure of photochromic 4,5-bis(4-acetyl-2,5-dimethyl-3-thienyl)-3-methyl-2,3-dihydro-1,3-oxazol-2-one was established by X-ray diffraction analysis. The molecule adopts an anti-parallel conformation similar to that of perfluorocyclopentene-bridged dithienylethenes.     

Synthesis of 2-D graphite-like and 3-D diamond-like silver(I) polymers with 1,3-imidazolidine-2-thione

Two metal–organic coordination polymers, [Ag₂(imdt)₃(OAc)₂] _n (1) (imdt = 1,3-imidazolidine-2-thione, OAc = CH₃COO^?) and [Ag(imdt)Cl] _n (2), were synthesized under similar conditions by using Et₃N (triethylamine) as buffering agent. X-ray diffraction shows that 1 crystallizes in the monoclinic system, C2 /c space group, a = 13.822(5) Å, b = 9.082(3) Å, c = 16.965(6) Å, V = 2114.2(14) ų, Z = 8, D _c = 2.012 g cm^?3. Compound 2 crystallizes in the orthorhombic system, P2₁2₁2₁ space group, a = 7.993(6) Å, b = 7.993(6) Å, c = 10.548(7) Å, V = 673.9(7) ų, Z = 4, D _c = 2.419 g cm^?3. Both 1 and 2 exhibit different architectures due to their different anions. Compound 1 shows a 2-D graphite-like network structure and 2 shows a 3-D diamond-like network structure.     

Synthesis and crystal structures of polynuclear complexes of Cu with 1-methyl-1,3-imidazoline-2-thione

Reactions of equimolar solutions of copper(I) halides with 1-methyl-1,3-imidazoline-2-thione (SC₄H₆N₂) in acetonitrile have yielded a trinuclear complex, {Cu₃(η¹-Br)₃(μ-SC₄H₆N₂)₃} · CH₃CN 1, and 1D polymer, {Cu₂(μ-I)₂(μ-SC₄H₆N₂)₂}_n2. The thio-ligands/halogens adopt μ-S, η¹-X or μ-X modes. There is weak interaction between trinuclear units {Cu···Br, 3.025 Å} and Cu···Cu contacts lie in the range, 2.974(2)–3.650(2) Å. Polymer 2 has alternating Cu₂I₂ and Cu₂S₂ cores involving sulfur/iodine bridging in a twisted ribbon type arrangement with short Cu···Cu distances {2.6912(9) and 2.785(9) Å}, respectively. The polynuclear complexes in dimethyl sulfoxide exhibit intense fluorescent bands {λ_em = 319 (1) and 322 (2)}.     

Photochromic dihetarylethenes. 10. Photochromic 1,2-bis[2-(benzothiazol-2-yl)-3-thienyl]- and 1,2-bis[2-(benzothiazol-2-yl)benzothiophen-3-yl]ethenes

Dithienylethenes containing the thiophene rings with benzothiazolyl substituents in position 2 were synthesized. 1,2-Bis[2-(benzothiazol-2-yl)benzothiophen-3-yl]hexafluorocyclopentene and 1,2-bis[2,5-di(benzothiazol-2-yl)-3-thienyl]hexafluorocyclopentene possess photochromic properties. The open forms of 1,2-bis(2-benzothiazolylhetaryl)ethenes fluoresce, but introduction of the benzothiazole rings into dihetarylethenes significantly lowers the fatigue resistance of photochromes and favors thermal reversibility.     

Photochromic dihetarylethenes. 11. Synthesis and photochromic properties of diarylethenes containing furan or furopyrimidine bridges

Procedures were developed for the synthesis of substituted bis(2,5-dimethyl-3-thienyl)furans based on 1,2-bis(2,5-dimethyl-3-thienyl)-2-hydroxyethanone. Dithienylethene structures in which the ethene fragment is involved in the furan or furopyrimidine system possess photochromic properties and their open forms exhibit fluorescence.     

Interaction of benzimidazole-2-thione with propargyl bromide and 1,3-dibromopropyne

Interaction of benzimidazole-2-thione with propargyl bromide under found conditions permitted the direct synthesis of 2-(2-propynylsulfanyl)-3H-1,3-benzimidazolium bromide, the base 2-(2-propynylsulfanyl)-1H-1,3-benzimidazole, stable crystalline 2-(1,2-propadienylsulfanyl)-1H-1,3-benzimidazole, and 3-methyl[1,3]thiazolo[3,2-a][1,3]benzimidazole. The reaction of benzimidazole-2-thione with 1,3-dibromopropyne in chloroform or absolute methanol gave 2-(3-bromo-2-propynylsulfanyl)-3H-1,3-benzimidazolium bromide, and in absolute methanole in the presence of a twofold excess of sodium methoxide the reaction proceeded stereo-and regioselectively to give 3-[(Z)-bromomethylidene][1,3]thiazolo[3,2-a][1,3]benzimidazole. Presented to Academician B. A. Trofimov on his 70^th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, 1399–1405, September, 2008.     

HSCN condensation with ulosides: preferred formation of carbohydrate-fused hemiaminals of the 4-hydroxy-1,3-oxazolidine-2-thione type

Selected ulofuranosides and ulopyranosides react with thiocyanic acid to give good yields of stable carbohydrate-fused hemiaminal 1,3-oxazolidine-2-thiones.     

Synthesis of substituted 2-amino-1,3-thiazine-6-thiones

The reaction of thiourea with l-acyl-2-bromoacetylenes in AcOH in the presence of BF₃·Et₂O affords 2-amino-4-phenyl(2-thienyl)-1,3-thiazine-6-thiones in high yields. Published inIzvestiya Akademii Nauk. Seriya Khimicheskaya. No. 11, pp. 1947–1949, November, 2000.     

Hydrogen-bond networks of 1,3-imidazolidine-2-thione: synthesis and structures of complexes of silver(I), copper(I), cadmium(II) and zinc(II)

Solution reactions of silver(I), copper(I), cadmium(II) and zinc(II) salts with 1,3-imidazolidine-2-thione (imdt) under diverse conditions yielded four complexes: [Cd(SC₃H₆N₂)₂(Ac)₂] (1), [Zn(SC₃H₆N₂)₂(Ac)₂] (2), [Cu₂(SC₃H₆N₂)₆]SO₄ (3) and [Ag₂(SC₃H₆N₂)₆]SO₄ (4). Complexes 1 and 2 are 1D and 2D hydrogen-bond aggregations. Complexes 3 and 4 are isostructural 3D hydrogen-bond networks. The diverse coordination modes of imdt and different anions are the major factors for three distinct hydrogen-bond structures.     

配合物{[Cu(hmtade)][Ni(dmit)2]}2·4DMSO的合成、表征及晶体结构

合成了配合物{[Cu(hmtade)][Ni(dmit)2]}2·4DMSO(1)(hmtade为5,7,7,12,14,14-六甲基-1,4,8,11-四氮杂环十四-4,11-二烯; dmit为1,3-二硫杂环戊二烯-2-硫酮-4,5-二硫醇; DMSO为二甲亚砜), 采用元素分析、红外光谱和紫外-可见光谱进行了表征, 并用X射线衍射法测定了晶体结构. 该晶体属于单斜晶系, P21/n空间群; 晶胞参数: a=1.49952(6) nm, b=1.77229(7) nm, c=3.1275(1) nm, β=102.442(1)°, V=8.1163(5) nm3, Dc=1.558 Mg/m3, Z=8, F(000)=3944, μ(Mo Kα)=1.637 mm-1, S=1.016, (Δ/σ)max=0.001, R1=0.0673, wR2 =0.1672[I>2σ(I)]. 晶体结构研究表明, 配合物{[Cu(hmtade)]·[Ni(dmit)2]}2·4DMSO包含2个[Cu(hmtade)][Ni(dmit)2]子单元. 每个子单元中, 1个dmit中的1个S原子与Cu及Ni配位, 形成异双核Cu—Ni配合物. 其中Cu(Ⅱ)为五配位的四方锥构形, Cu—N键长在0.1949(5)~0.2007(4) nm范围内, Cu—S键长分别为0.28913(18)和0.28952(18) nm; 配阴离子[Ni(dmit)2]2-为畸变四方形, Ni—S键长在0.21729(16)~0.21905(17) nm范围内. 溶剂分子DMSO与配体hmtade形成了N—H…O氢键. 通过分子内S…S和S…H短接触形成了二聚体, 二聚体之间通过S…S短接触形成一维链状结构, 并通过S…S, S…H和C…H短接触进一步形成二维和三维结构.     

Synthesis of 1,3-dithiole-2-thiones and tetrathiafulvalenes using oligo-(1,3-dithiole-2,4,5-trithione). (Review)

Methods for the synthesis of 1,3-dithiole-2-thiones, based on [4+2] cycloaddition of the 1,3-dithiole-2,4,5-trithione oligomer to various unsaturated acyclic, carbocyclic, and heterocyclic compounds, are reviewed. Methods for the production of substituted tetrathiafulvalenes, which can be regarded as derivatives of bis(ethylenedithio)tetrathiafulvalene, from 1,3-dithiole-2-thiones synthesized by this method are described. Dedicated to the memory of Professor O. Neilands. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 483–502, April, 2006.     

Addition of 1,2- and 1,3-Dithiols to 2-alkoxypropenals - a New Method for the Production of Substituted Dithiacycloalkanes

The reaction of 2-alkoxypropenals with ethane-1,2-dithiols and propane-1,3-dithiols under various conditions was studied by ¹H NMR and chromato-mass spectrometry. Under kinetically controlled conditions at 20° in the absence of catalysts the addition of dithiols takes place according to the Markovnikov rule. The primary adducts are unstable and are quickly converted into the corresponding substituted 1,4-dithiacycloheptane or 1,4-dithiane. The latter in turn can be converted under the reaction conditions or at high temperature into a thiolane derivative. The reaction of 2-ethoxypropenal with a twofold excess of ethane-1,2-dithiol at 60°C in the presence of p-toluenesulfonic acid leads to 2-methyl-2,2'-bi(dithiolane)     

Photochromic dihetarylethenes. 19. Synthesis of 1,2-dihetarylethenes on the basis of thieno[3,2-b]pyrroles linked by a maleimide bridge

New photochromic 1,2-dihetarylethenes containing maleimide-bridged thieno[3,2-b]pyrrole fragments with aliphatic and aromatic substituents at the nitrogen atom were synthesized.     

Synthesis and structural characterization of ruthenium complexes with 1-aryl-imidazole-2-thione

Treatment of [RuCl₂(PPh₃)₃] with 2 equiv. Himt^MPh (Himt^MPh?=?1-(4-methyl-phenyl)-imidazole-2-thione) in the presence of MeONa afforded cis-[Ru(κ ²-S,N-imt^MPh)₂(PPh₃)₂] (1), while interaction of [RuCl₂(PPh₃)₃] and 2 equiv. Himt^MPh in tetrahydrofuran (THF) without base gave [RuCl₂(κ ¹-S-Himt^MPh)₂(PPh₃)₂] (2). Treatment of [RuHCl(CO)(PPh₃)₃] with 1 equiv. Himt^MPh in THF gave [RuHCl(κ ¹-S-Himt^MPh)(CO)(PPh₃)₂] (3), whereas reaction of [RuHCl(CO)(PPh₃)₃] with 1 equiv. of the deprotonated [imt^MPh]^? or [imt^NPh]^? (imt^NPh?=?1-(4-nitro-phenyl)-2-mercaptoimidazolyl) gave [RuH(κ ²-S,N-imt^RPh)(CO)(PPh₃)₂] (R?=?M 4a, R?=?N 4b). The ruthenium hydride complexes 4a and 4b easily convert to their corresponding ruthenium chloride complexes [RuCl(κ ²-S,N-imt^MPh)(CO)(PPh₃)₂] (5a) and [RuCl(κ ²-S,N-imt^NPh)(CO)(PPh₃)₂] (5b), respectively, in refluxing CHCl₃ by chloride substitution of the RuH. Photolysis of 5a in CHCl₃ at room temperature afforded an oxidized product [RuCl₂(κ ²-S,N-imt^MPh)(PPh₃)₂] (6). Reaction of 6 with excess [imt^MPh]^? afforded 1. The molecular structures of 1·EtOH, 3·C₆H₁₄, 4b·0.25CH₃COCH₃, and 6·2CH₂Cl₂ have been determined by single-crystal X-ray crystallography.     

Photochromic Dihetarylethenes. 12. Synthesis of 5-Alkyl-2-(1,3,4-oxadiazol-2-yl)thiophenes and Their Photochromic Derivatives

Photochromic derivatives of 5-alkyl-2-(1,3,4-oxadiazol-2-yl)thiophenes have been synthesized for the first time. Their photochromic and fluorescent properties have been studied.     

Heterocyclic thioamides of copper(I): Synthesis and crystal structures of copper complexes with 1,3-imidazoline-2-thiones in the presence of triphenyl phosphine

Reaction of copper(I) chloride with 1,3-imidazoline-2-thione (imzSH) in the presence of Ph₃P in 1:2:2 or 1:1:2 (M:L:PPh₃) molar ratios yielded a compound of unusual composition, [Cu₂(imzSH)(PPh₃)₄Cl₂] · CH₃OH (1), whose X-ray crystallography has shown that its crystals consist of four coordinated [CuCl(1κS-imzSH)(PPh₃)₂] (1a), and three coordinated [Cu(PPh₃)₂Cl] (1b) independent molecules in the same unit cell. In contrast, crystals of complexes of copper(I) bromide/iodide are formed by single molecules of [CuBr(1κS-imzSH)(PPh₃)₂] · H₂O (2) and [CuI(1κS-imzSH)(PPh₃)₂] (3), respectively, similar to molecule 1a. The related ligand, 1,3-benzimidazoline-2-thione (bzimSH) formed a complex [CuBr(1κS-bzimSH)(PPh₃)₂] · CH₃COCH₃ (4), similar to 2. The formation of 1a and 1b has been also revealed by NMR spectroscopy. The NMR spectra of 2–4 also showed weak signals indicating formation of compounds similar to 1b. It reveals that the lability of the Cu–S bond varies in the order: Cl ? Br ∼ I. Weak interactions {e.g. C–H?π electrons of ring, –NH?halogens/oxygen, C–H?halogens/oxygen, π?π (between rings)} have played an important role in building 2D chains of complexes 1–4.     

The stereoselective addition of titanium(IV) enolates of 1,3-oxazolidin-2-one and 1,3-thiazolidine-2-thione to cyclic N-acyliminium ion. The total synthesis of (+)-isoretronecanol

(+)-Isoretronecanol (1) has been prepared in four steps and 36% overall yield via the diastereoselective addition of the titanium(IV) enolate derived from N-4-chlorobutyryl-1,3-thiazolidine-2-thione (3) to N-Boc-2-methoxypyrrolidine (5), which afforded 2-substituted pyrrolidine 7 in 84% yield (8:1 diastereoisomeric ratio), followed by reductive recovery of the chiral auxiliary and cyclization.