Synthesis and characterization of polymers of 1,4-hexadienes

The homopolymerization of trans-1,4-hexadiene, cis-1,4-hexadiene, and 5-methyl-1,4-hexadiene was investigated with a variety of catalysts. During polymerization, 1,4-hexadienes undergo concurrent isomerization reactions. The nature and extent of isomerization products are influenced by the monomer structure and polymerization conditions. Nuclear magnetic resonance (NMR) and infrared (IR) data show that poly(trans-1,4-hexadiene) and poly(cis-1,4-hexadiene) prepared with a Et₃Al/α-TiCl₃/hexamethylphosphoric triamide catalyst system consist mainly of 1,2-polymerization units arranged in a regular head-to-tail sequence. A 300-MHz proton NMR spectrum shows that the trans-hexadiene polymer is isotactic; it also may be the case for the cis-hexadiene polymer. These polymers are the first examples of uncrosslinked ozone-resistant rubbers containing pendant unsaturation on alternating carbon atoms of the saturated carbon-carbon backbone. Polymerization of the 1,4-hexadienes was also studied with VOCl₃- and β-TiCl₃-based catalysts. Microstructures of the resulting polymers are quite complicated due to significant loss of unsaturation, in contrast to those obtained with the α-TiCl₃-based catalyst. In agreement with the literature, there was no discernible monomer isomerization with the VOCl₃ catalyst system.     

Water-based Synthesis and Properties of a Scandium 1,4-Naphthalenedicarboxylate

A new scandium naphthalenedicarboxylate with the framework composition [Sc₂(1,4-NDC)₃] (H₂-1,4-NDC = 1,4-naphthalenedicarboxylic acid) was obtained under hydrothermal synthesis conditions. A structure model could be developed by a combination of 3D electron diffraction measurements and computationally assisted structure determination, which was further validated by a good agreement with the experimental powder X-ray diffraction pattern. The structure consists of isolated ScO₆ octahedra interconnected by the carboxylate groups of linker molecules to form chains. These chains are connected by the naphthalene-moieties to form a three-dimensional framework with square-shaped pores and the organic group pointing into the pores. Although very similar synthesis conditions were chosen, [Sc₂(1,4-NDC)₃] is not isostructural to aluminum naphthalenedicarboxylate [Al(OH)(1,4-NDC)], which crystallizes in a MIL-53 type structure. This can be traced back to the different inorganic building units that are observed. The compound was thoroughly characterized by elemental analysis, IR spectroscopy, sorption measurements, thermogravimetric analysis and luminescence measurements. [Sc₂(1,4-NDC)₃] exhibits a high thermal stability and a ligand-based blue luminescence in the solid state at room temperature.     

Additionsverbindungen zwischen Antimon(III)-Halogeniden und 1,4-Dithiacycloheptan

Addition Compounds between Antimony(III)-Halides and 1,4-Dithiacycloheptane SbCl₃, SbBr₃, and SbI₃ do form the addition compounds SbCl₃ · 1,4-Dithiacycloheptane, SbBr₃ · 1,4-Dithiaheptane and 2 SbI₃ · 1,4-Dithiacycloheptane from benzene solutions. The new compounds are only stable in the solid form. FIR spectra of the SbCl₃ and SbBr₃ complexes are recorded as well as the X-ray structure of the SbCl₃ compound.     

Synthesis and structures of two cobalt(II) coordination networks formed from aromatic polycarboxylates and 1,4-bis(imidazole-1-ylmethyl)benzene

Two Co(II) coordination polymers, [Co(Hbtc)(bix)] _n , (1) and [Co(1,4-bdc)(bix)H₂O] _n (2) (bix = 1,4-bis(imidazole-1-ylmethyl)benzene; H₃btc = benzene-1,3,5-tricarboxylic acid; 1,4-H₂bdc = benzene-1,4-dicarboxylic acid) have been synthesized under hydrothermal conditions and structurally characterized. X-ray structure analysis reveals that in polymer 1, 2D infinite grid-like frameworks are interconnected by hydrogen-bond interactions to result in a 3D supramolecular architecture, in which the three carboxylate groups of the H₃btc molecule adopt three different coordination modes. In polymer 2, 1,4-bdc ligands with cobalt atoms construct 1D zigzag chains which are bridged by bix ligands to form a 3D framework.     

Isomerization of unsaturated radicals. VI. Isomerization of 3-cyclopenlenyl and pentamethylene radicals

The 184.9 nm photochemistry 0f gaseous 3-methylcyclopentene and 3-methyl-1,4-pentadiene have been studied. Both photoexcited species decompose mainly through the primayy rupture of the C-CH₃ bond. Vibrationally excited 3-cyclopenennyl and pentamethylene radicals are formed in the primayy decomposition in the former and latter systems respectively. These radicals are connected through isomerization reactions: in the presence of DI, the isomers cyclopenten,, and trans-1,3-pentadtene and/or vinylcyclopropane are formed in both systems. The quantum yields depend on the pressure and the starting monomer: cyclopentene and cyclopentadiene are the major products from the photolysis of 3-methylcyclopentene + DI mixtures and only minor quantities of the other C₅H₈ compounds are formed. Cyclopentadiene is the major product of the photolysis of 3-methyl-1,4-pentadiene + O₂ mixtures whereas vinylcyclopropane and trans-1,3-pentadiene are the major C₅ producss of the photolysis of 3-methyl-1,4-pentadiene + DI mixtures. The geometries of 3-cyclopentenyl and of the structures at the six critical points in the torsional potential energy curve (TPEC) for rotation about the 2- and 3-C-C bonds in the open chain pentamethylene species have been optimized completely by ab initio RHF-SCF gradient methods. For the open-chain structures the bond orders, bond lengths and the free valence (primarily associated with the central carbon atom) all correspond to 1,4-pentadien-3-yl conformations. In the ground state there is a high barrier to formation of 3-cyclopentenyl from 1,4-pentadien-3-yl. The features (relative energies and torsionll barriers) of the TPEC for 1,4-pentadien-3-yl explain the ESR observations for the open chain C₅H₇ radical rotamers.     

A new type of palladium(0) complex having both electron-withdrawing and -donating sites in a ligand: 5,8-dihydro- and 5,8,9,10-tetrahydro-1,4-naphthoquinone complexes

A new type of palladium(0) complex, (5,8-dihydro-1,4-naphthoquinone)Pd(PPh₃)₂ and (5,8,9,10-tetrahydro-1,4-naphthoquinone)Pd(PPh₃)₂, having both olefin and quinone or dihydro-quinone sites in a ligand molecule was prepared. IR and ¹H NMR spectroscopic studies of these complexes suggested that it is the quinone or dihydro-quinone CC bond which is complexed to Pd. Ligand exchange reactions showed that the stability order of the olefinic quinone complexes was as follows: (1,4-naphthoquinone)Pd(PPh₃)₂ > (5,8-dihydro-1,4-naphthoquinone) Pd(PPh₃)₂>(5,8,9,10-tetrahydro-1,4-naphthoquinone)Pd(PPh₃)₂.     

Reactivity of N-arylsulfonyl-1,4-benzoquinone imines. Reaction with hydrazoic acid

N-Arylsulfonyl-2-halo-1,4-benzoquinone imines react with hydrazoic acid in boiling acetic acid via two pathways: the 1,4-addition and nucleophilic replacement of the halogen atom by an azido group, followed by the 1,4-addition of HN₃. In the reaction of N-arylsulfonyl-2,6-dihalo-1,4-benzoquinone imines with hydrazoic acid, both halogen atoms are replaced by azido groups, while N-p-tolylsulfonyl-2-methyl-1,4-benzoquinone imine takes up HN₃ molecule according to the 1,4-addition pattern.     

Differences in the coordinating ability of water,perchlorate and tetrafluoroborate toward copper(I). The x-ray crystal structures of [Cu(1,4-thioxane)3OClO3], [Cu(1,4-thioxane)3OH2]BF4 and [Cu(1,4-thioxane)4BF4

Summary Crystal structure determinations of the non-isomorphous salts, Cu(1,4-thioxane)₃(ClO₄) and Cu(1,4-thioxane)₄(BF₄) were carried out. The former compound was shown to contain strongly coordinated perchlorate while the later contains ionic tetrafluoroborate. For the coordinated perchlorate group, Cu-O is 2.278(8) Å. A third compound, Cu(1,4-thioxane)₃(H₂O)(BF₄), was also characterized by x-ray crystallography, and contains a coordinated water molecule (with Cu-O 2.234(7) Å) that is hydrogen bonded to ionic tetrafluoroborate. All three complexes have approximately tetrahedral geometry. The copper(I) atom is coordinated to the sulfur atoms of the 1,4-thioxane rings. In each of the complexes, one of the 1,4-thioxane six-membered rings is coordinatedvia an equatorial ring position and the remaining two or three rings are coordinatedvia an axial position. The compound, Cu(1,4-thioxane)₄(ClO₄), was also prepared and found to be isomorphous with Cu(1,4-thioxane)₄ (BF₄), enabling a comparison to be made between the i.r. spectra of ionic and coordinated perchlorate in similar complexes.     

Efficient and Convenient Synthesis of 1,4-Benzoxazines, 1,4-Benzothiazines,Spiro-1,4-benzoxazines,and Spiro-1,4-benzothiazines

An efficient, convenient synthesis of 1,4-benzoxazines, 1,4-benzothiazines, spiro-1,4-benzoxazines, and spiro-1,4-benzothiazines derivatives was accomplished in good yields via the novel intramolecular cyclization mediated by mild base K₂CO₃ in ethanol solvent. A variety of substrates can participate in the process with good yields, making this methodology have broad applicability. All the structures of synthesized compound have been confirmed by spectral analysis.

Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications ^® to view the free supplemental file.     

Characterization of two linear chain compounds: Ferromagnet NiCl2(CH3OH)2(1,4-dioxane)0.5 (1) and paramagnet [NiCl2(H2O)2(1,4-dioxane)](1,4-dioxane) (2)

The solvent-mediated crystal-to-crystal transformation was observed from yellow crystal of NiCl₂(CH₃OH)₂(1,4-dioxane)_0.5 (1) to green crystal of [NiCl₂(H₂O)₂(1,4-dioxane)](1,4-dioxane) (2) under high humidity or adding of H₂O in CH₃OH/1,4-dioxane solution. The μ-Cl₂ bridge in 1 replaced by 1,4-dioxane bridge in 2. In 1, the chlorine-bridged linear chains of NiCl₂(CH₃OH)₂ and 1,4-dioxane molecules stack along the b- and c-axis alternatively with hydrogen bonds intrachain, interchain, between chain and solvent. These hydrogen bonds and dipolar interaction between ferromagnetic coupling chlorine-bridged chains result in long-range ferromagnetic ordering at 3.1 K and a strong frequency dependence of the ac-susceptibilities associated to domain structures with very large shape anisotropy was observed below 3.1 K. In 2, layers of 1,4-dioxane-bridged linear chains of NiCl₂(H₂O)₂(1,4-dioxane) are intercalated by layer of 1,4-dioxane molecules with hydrogen bonds between chain and solvent. Compound 2 is paramagnet to 2 K.     

The reactions of trifluoromethyl and trichloromethyl radicals with conjugated and methylene-interrupted dienes and enynes

The photochemical addition of CF₃I to buta-1,3-diene and vinylacetylene in the gas phase gave 1,4-adducts as the main products. In gas phase reactions only products derived from hydrogen abstraction were detected in the CF₃I/penta-1,3-diene system, but the 1,4-adducts again predominated in the liquid phase. CCl₃Br similarly gave a mixture of 1,2- and 1,4-adducts, the latter predominating, on photochemical reaction with penta-1,3-diene. The 1,2-adduct was the main product from the CCl₃Br/pent-1-en-4-yn reaction, but some hydrogen abstraction was observed. The preference shown by conjugated dienes to give 1,4-adducts in the $\text{trans}$- configuration is interpreted in terms of steric factors and the propensity of dienes to adopt the $\text{s}$-$\text{trans}$ conformation.     

Temperature dependence of unperturbed dimensions for stereoirregular 1,4-polybutadiene and poly(α-methylstyrene)

The temperature coefficient of chain dimensions, d ln〈r²〉₀/dT, was determined for stereoirregular 1,4-polybutadiene and poly(α-methylstyrene) via dilute solution viscometry. The 1,4-polybutadiene was examined in oligomeric 1,4-polybutadiene (an athermal solvent), and poly(α-methylstyrene) was evaluated under near-theta conditions using 1-chloro-n-alkanes as solvents. Both approaches minimize the potential for influence by specific solvent effects. The resulting temperature coefficients, ?0.1₀ × 10^?3 deg^?1 for 1,4-polybutadiene and ?0.3₀ × 10^?3 deg^?1 for poly(α-methylstyrene) are in excellent agreement with rotational isomeric state calculations.     

Geminal Dicationic Ionothermal Synthesis of One Three-Dimensional Luminescent Strontium(II) Coordination Polymer Based on 1,4-Naphthalenedicarboxylate Acid

One three-dimensional Sr(II) coordination polymer [C₆(MIm)₂][Sr₃(1,4-NDC)₄] (I) (C₆(MIm)₂ = 1,3-bis(3-methylimidazolium-1-yl)hexyl, 1,4-H₂NDC = 1,4-naphthalenedicarboxylate acid) has been synthesized using an ionothermal method and structurally characterized by IR spectroscopy, UV-Vis spectroscopy, XRPD, and X-ray single-crystal structure analysis (СIF file CCDC 1033958). Two types of strontium centers are bridged by two coordination modes of 1,4-H₂NDC ligands to form a Sr(II) chain. Each Sr(II) chain is crossconnected to four other chains to generate a 3D coordination polymer, in which C₆(MIm) ₂ ²⁺ cations as charge balancing species are filled in the channels of the anionic framework. The polymeric solid of I exhibits strong luminescent emission at room temperature.     

3-D frameworks assembled by lanthanide dimers with 1,4-cyclohexanedicarboxylic acid and 1,10-phenanthroline via hydrogen bonds and π–π stacking interactions

Two complexes [Ln(e,a-cis-1,4-chdc)(e,a-cis-1,4-Hchdc)(phen)(H₂O)]₂?10H₂O (Ln = Eu, 1; Tb, 2, 1,4-H₂chdc = 1,4-cyclohexanedicarboxylic acid; phen = 1,10-phenanthroline) have been synthesized and structurally characterized by single-crystal X-ray diffraction. Both complexes are doubly e,a-cis-1,4-chdc-bridged dimers. The e,a-cis-1,4-Hchdc, phen, and water molecules bond to Ln³⁺, forming nine-coordinate complexes. 3-D supramolecular frameworks are constructed by hydrogen bonds and π–π stacking interactions. Luminescence spectra exhibit the ⁵D₀ → ⁷F _J (J = 0–4) and ⁵D₄ → ⁷F _J (J = 6–3) transitions of Eu³⁺ for 1 and Tb³⁺ ion for 2, respectively.     

A new synthesis of 3-hydroxy-2,3-dihydro-1,4-benzodioxin-2-carboxamides and 3-aminomethylene-1,4-benzodioxin-2(3H)-one derivatives

The 1,4-benzodioxin-2-carboxylic esters or carboxamides react with nucleophilic amines to give access to 3-hydroxy-2,3-dihydro-1,4-benzodioxin-2-carboxamides and 3-aminomethyn-1,4-benzodioxin-2(3H)-one precursors of potential therapeutical compounds. The basic environment (K₂CO₃ or amine) facilitates the process.     

Investigation of 2,3'-Biquinolyl. 11. Regioselectivity in the Hydroxylation of 1-Alkyl-3-(2-quinolyl)quinolinium Halides

The hydroxylation of 1-alkyl-3-(2-quinolyl)quinolinium halides by an alkaline solution of K₃[Fe(CN)₆] in aqueous 1,4-dioxane leads to a mixture of 1-alkyl-3-(2-quinolyl)-1,2-dihydro-2-quinolones and 1-alkyl-3-(2-quinolyl)-1,4-dihydro-4-quinolones with predominance of the former. The use of the system of K₃[Fe(CN)₆]/Mg(OH)₂ in aqueous 1,4-dioxane leads to the regiospecific formation of 1-alkyl-3-(2-quinolyl)-1,4-dihydro-4-quinolones.     

Construction of 3,9-diazatetraasteranes and 3,9-diazatetracyclododecanes by photocycloaddition reaction of 1,4-dihydropyridines: Experimental and theoretical investigation

A photocycloaddition reaction of ethyl 1,4-diaryl-1,4-dihydropyridine-3-carboxylate for the construction of 3,9-diazatetraasteranes (P₁) and 3,9-diazatetracyclododecanes (P₂) is reported for the first time. The types of reaction product clearly differ with solvent, regardless of the irradiation wavelength. The difference in P₁ and P₂ lies in the second step of the intramolecular [2 + 2] photocyclization. In order to further investigate this phenomenon and gain a deeper understanding of the photochemical behavior of 1,4-dihydropyridines, DFT and TDDFT theoretical calculations are performed. The results provide a good explanation for the formation of 3,9-diazatetraasteranes and 3,9-diazatetracyclododecanes.     

Syntheses and characterization of four coordination compounds derived from 10,11,12,13-tetrahydro-4,5,9,14-tetraaza-benzo[b]triphenylene and benzene-dicarboxylic acids

[Co₂(TTBT)₄(1,2-BDC)₂] _n ?·?4nH₂O (1), [Pb₂(TTBT)₂(1,3-BDC)₂] _n ?·?nTTBT?·?2nH₂O (2), [Fe(TTBT)(1,4-BDC)(H₂O)] _n (3), and [Zn(TTBT)(1,4-BDC)(H₂O)] _n (4) have been hydrothermally synthesized by self-assembly of TTBT (TTBT?=?10,11,12,13-tetrahydro-4,5,9,14-tetraaza-benzo[b]triphenylene), benzene-dicarboxylic acid ligands 1,2-H₂BDC, 1,3-H₂BDC or 1,4-H₂BDC (1,2-H₂BDC?=?1,2-benzenedicarboxylic acid, 1,3-H₂BDC?=?1,3-benzenedicarboxylic acid, 1,4-H₂BDC?=?1,4-benzenedicarboxylic acid), and various metal salts. Compound 1 has dinuclear cluster units, four dimeric Co₂ units connected to form a 32-membered ring via weak offset π–π interactions, which are further stacked via strong π–π interactions to form a 3-D supramolecular framework. Complex 2 contains 2-D layers with rhombohedral grids, which are connected to a 3-D structure by π–π interactions. 3 and 4 feature 1-D infinite chains, which are further extended by strong π–π interactions and O–H···O hydrogen bonds resulting in 3-D supramolecular architectures. The photoluminescent properties of 2 and 4 have also been investigated.     

Preparation and characterization of binuclear CuII complexes derived from diamines and dialdehydes

New macrocyclic complexes were synthesized by template reaction of 1,7-bis(2-formylphenyl)-1,4,7-trioxaheptane, 1,4-bis(2-carboxyaldehydephenoxy)butane or 1,3-bis(2-carboxyaldehydephenoxy)propane with 1,4-bis(2-aminophenoxy)butane, 1,3-bis(2-aminophenoxy)butane, 1,4-bis(4-chloro-2-aminophenoxy)butane or 1,3-bis(4-chloro-2-aminophenoxy)butane and Cu(NO₃)₂ ·?3H₂O or Cu(ClO₄)₂ ·?6H₂O, respectively. The complexes have been characterized by elemental analysis, IR, ¹H and ¹³C NMR, UV–Vis spectra, magnetic susceptibility, conductivity measurements and mass spectra. All complexes are diamagnetic and binuclear.     

Copolymerization of dienes with neodymium tricarboxylate-based catalysts and cis-polymerization mechanism of dienes

It was found that poly(butadiene), poly(isoprene), and poly(2,3-dimethylbutadiene) with high cis-1,4 content were obtained with Nd(OCOR)₃–(i-Bu)₃Al–Et₂AlCl catalysts (R = CF₃, CCl₃, CHCl₂, CH₂Cl, CH₃) in hexane at 50°C [cis-1,4 content: poly(BD), > 98%; poly(IP), ≥ 96%; poly(DMBD), ≥ 94%]. Copolymerization of IP and styrene (St) was carried out at various monomer feed ratios to evaluate the monomer reactivity ratio and cis-1,4 content of the diene unit and then to elucidate the cis-1,4 polymerization mechanism of IP. The cis-1,4 content of the IP unit in the copolymers decreased with increasing St content in the copolymers. The cis-1,4 polymerization was disturbed by incorporating St unit in the copolymers, since the penultimate St unit hardly coordinates to the neodymium metal, resulting in a decrease of the cis-1,4 content in the copolymers. That is, the cis-1,4 polymerization of IP is suggested to be controlled by a back-biting coordination of the penultimate diene unit. On the other hand, in the case of poly(BD-co-IP) and poly(BD-co-DMBD), the cis-1,4 content of the BD, IP, and DMBD units in the copolymers was almost constant (cis: 94–98%), irrespective of the monomer feed ratios and polymerization temperature. Consequently, the penultimate IP and DMBD units favorably control the terminal BD, IP, or DMBD unit to the cis-1,4 configuration through the back-biting coordination. For the monomer reactivity ratios, a clear difference was observed in each system: r_BD = 1.22, r_IP = 1.14; r_BD = 40.9, r_DMBD = 0.15. Low polymerizability of DMBD was mainly ascribed to the steric effect of the methyl substituents. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1707–1716, 1998