Pyridine Solution Research Articles

Ligand‐Free Deltahedral Clusters of Silicon in Solution: Synthesis, Structure, and Electrochemistry of Si92‐.

AbstractFor Abstract see ChemInform Abstract in Full Text.

A novel degradation pathway of Zn (dmid) (phen)2 in pyridine

The light-oxidation degradation processes of Zn(dmid)(phen)2 (dmid=4,5-dimercapto-1, 3-dithiole-2-one, phen=1, 10-phenanthroaline) in pyridine solvent has been monitored. It has been found under the light, dmid2− of Zn(dmid)(phen)2 in pyridine solution could generate NCS− and NCS− replaces dmid2− to form Zn(NCS)2 (phen)2 simultaneously. The crystal structure of Zn(NCS)2(phen)2 has been determined. In the crystal of Zn(NCS)2(phen)2, two NCS− ligands are arranged in syn-configuration, and there is strong ππ interaction between the two adjacent parallel phen.

Ligand-Free Deltahedral Clusters of Silicon in Solution: Synthesis, Structure, and Electrochemistry of Si92-

Deltahedral nine-atom clusters of silicon, Si(9)(2-), were synthesized by mild oxidation of a liquid ammonia solution of K(12)Si(17) with Ph(3)GeCl in the presence of 18-crown-6 (1,4,7,10,13,16-hexaoxacyclooctadecane) or 2,2,2-crypt (4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo[8.8.8]hexacosane). The clusters were structurally characterized in [K(18-crown-6)](2)Si(9).C(5)H(5)N (yellow; orthorhombic, Pnma; a = 14.013(1), b = 18.108 (1), c = 18.320 (1) A; Z = 4) crystallized from a pyridine solution of the product of the aforementioned reaction in liquid ammonia. Si(9)(2-) is the first unequivocally characterized nine-atom cluster of group 14 with a charge of 2-. In addition to pyridine, the product from the reaction in liquid ammonia is also soluble in DMF, and the Si(9)(2-) clusters were characterized by mass spectrometry in such a solution. The more reduced clusters Si(9)(3-) have also been crystallized from pyridine solution. Cyclic voltammetry in both pyridine and DMF solutions clearly shows the Si(9)(2-)/Si(9)(3-) redox couple as one-electron reversible process. The structural similarities and differences between Si(9)(3-) and Si(9)(2-) are discussed herein.

A p-cyanophenylimido hexamolybdate: preparation and structure of [(n-C4H9)4N]2[Mo6O18(N-p-C6H4CN)] †

Abstract The title compound has been prepared through reaction of the corresponding arylimino-triphenylphosphorane with [(n-C4H9)4N]2[Mo6O19] in hot pyridine solution. The single crystal X-ray structure of the title compound has been determined. To cite this article: H. Kwen et al., C. R. Chimie 8 (2005).

Preparation of Phthalocyanine Modified Electrodes. An Electrophoretic Approach

AbstractNi(II) and Co(II) phthalocyanines were deposited from their solutions in pyridine. The resulting modified electrodes exhibited catalytic activity in alkaline media.

Metal Complexes of meso-Amino-octaethylporphyrin and the Oxidation of NiII(meso-amino-octaethylporphyrin)

The crystal structures of meso-NH2-OEPH2, NiII(meso-NH2-OEP), and CuII(meso-NH2-OEP) (where OEP is the dianion of meso-amino-octaethylporphyrin) have been determined to examine the effects of the meso-substituent on the geometry of the ligand. CuII(meso-NH2-OEP) has a nearly planar geometry while the free ligand itself and NiII(meso-NH2-OEP) have ruf conformations. NiII(meso-NH2-OEP) is much less reactive toward oxidation than are (py)2FeII(meso-NH2-OEP), ClFeIII(meso-NH2-OEP), or NiII(meso-HO-OEP), which all undergo oxidation in pyridine solution when exposed to dioxygen. Treatment of NiII(meso-NH2-OEP) with iron(III) chloride in chloroform solution does result in oxidation of the ligand in two separate processes. One involves oxygenation at the trans-meso position, while the other results in ring cleavage and removal of the amino function. The open-chain tetrapyrrole complex, NiII(OEB-CO2Et), has been characterized by single-crystal X-ray diffraction and shown to contain a helical ligand with a four-coordinate nickel ion.

A synthetic, structural, and113Cd NMR study of cadmium complexes of 1,3-thiazolidine-2-thionate, including the structures of Cd(C3H4NS2)2, (Cd(C3H4NS2)2(C5H5N)3·C5H5N, and (Ph4P)2[I2Cd(µ-C3H4NS2)2CdI2

The crystallization of cadmium bis(1,3-thiazolidine-2-thionate), Cd(C3H4NS2)2(1), is reported. Freshly prepared 1 reacts with Ph4P+X–in a 1:2 ratio to give (Ph4P)2[Cd2(C3H4NS2)2X4] (X = I (4) or Br (5)). Crystallization of 1 from pyridine produces a solvate 7, which loses pyridine readily. X-ray analyses show that 1 has a polymeric sheet structure in which the C3H4NS2–ligands act as bidentate bridges through N and the exocyclic S and the Cd has a CdN2S2kernel; 5 is isomorphous with 4, which contains a dimeric anion again with bridging through the N and exocyclic S of the heterocyclic ligands; and 7 is Cd(C3H4NS2)2(C5H5N)3·C5H5N, containing trigonal bipyramidal Cd(C3H4NS2)2(C5H5N)3molecules, in which the C3H4NS2–ligands, both of which are monodentate and in equatorial positions, occur as a unique combination of S- and N-bound. Cadmium-113 NMR data for 1 in pyridine solution and solid-state CP-MAS113Cd data for 1, 7, bis(pyridinium-4-thiolate)cadmium, and tetrakis(pyridinium-2-thiolate)cadmium nitrate are reported and discussed. The compound 1 has chemical and NMR spectroscopic properties that make it a useful standard for solid-state CP-MAS113Cd NMR spectroscopy. Key words: cadmium, 1,3-thiazolidine-2-thionate, X-ray analysis, solid-state113Cd NMR,113Cd NMR standard compound.

Isomerisation of aldoses in pyridine in the presence of aluminium oxide

Addition of aluminium oxide to boiling pyridine solutions of D-xylose, L-arabinose, D-mannose and D-glucose strongly increased the reaction rate of the aldose-ketose transformation. The maximum content of 2-ketose was reached after less than 2h for the aldopentoses and 3h for the aldohexoses. D-Threo-2-pentulose (xylulose) was prepared from D-xylose, and isolated as its O-isopropylidene derivative, the yield was nearly twice that compared to that usually obtained in the classical Lobry de Bruyn-Alberda van Ekenstein transformation in pyridine.

New Efficient Synthesis of [UI4(MeCN)4]. X-ray Crystal Structures of [UI2(MeCN)7][UI6], [UI4(py)3], and [U(dmf)9]I4

Reaction of UCl4 and excess Me3Sil in acetonitrile provides a convenient route to [Ul4(MeCN)4] (1), which was isolated in excellent yield and crystallized in acetonitrile as the ion pair complex [Ul2(MeCN)7][Ul6] (2). Compound 1 was transformed in pyridine (py) and dimethylformamide (dmf) into the Lewis base adducts [Ul4(py)3] (3) and [Ul4(dmf)6] (4). Crystals of 3 and [U(dmf)9]l4 (5) were obtained by slow diffusion of diethyl ether into pyridine or dmf solutions of 1; compound 5 is the first tetracationic {U4+} entity to have been crystallographically characterized.

Preparation, characterization, and metal binding behavior of novel chelating resins containing sulfur and polyamine

AbstractSeveral kinds of polyamine‐type chelating resins containing sulfide were synthesized by the reaction of polyamines, such as ethanolamine (EA), ethylenediamine (EDA), diethylenetriamine (DETA), and triethylenetetramine (TETA), with poly[4‐vinylbenzyl (2‐benzenesulfonate ethyl) sulfide] (PSMP), which was itself prepared by the reaction of poly[4‐vinylbenzyl (2‐hydroxyethyl) sulfide] (PSME) with benzenesulfonal chloride in pyridine solution. Factors affecting syntheses of PSMP, such as solvents, reaction temperature and time, and ratio of reactants, were investigated. Structures of the above resins were confirmed by FTIR and elemental analysis. Their surface morphology and pore structures were observed on a SEM and determined by the BET method, respectively. Adsorption experiments showed that these resins exhibit better adsorption selectivity for noble metal ions and Hg(II) than other heavy ones. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 95: 1558–1565, 2005

Improved Dimerization of Diethyl Acetonedicarboxylate Leading to Polyfunctionalized Phenol

When a pyridine solution of sodium enolate of diethyl acetonedicarboxylate was heated in the presence of p-nitrophenol, the dimerization readily proceeded under mild conditions to give polyfunctionalized phenol, ethyl {2,4-bis(ethoxycarbonyl)-3,5-dihydroxyphenyl}acetate, in moderate yield.

Synthesis and characterization of sulfathiazole-pyridine solvate polymorphs

Tetragonal and monoclinic polymorphs of sulfathiazole-pyridine solvate (C9H9N3O2S2C5H5N) were crystallized from propanol–pyridine solutions. The two polymorphs are unstable under ambient conditions but can be stored for a long time under pyridine vapor. TG and DSC of freshly prepared samples prove the decomposition of the solvates with pyridine vapor and sulfathiazole I as products. Thermodynamic estimate shows that the decomposition can be considered just a sum of two processes: (1) high-energy sublimation of pyridine and (2) low-energy structural transformation of the remaining sulfathiazole.

Synthesis and characterization of new aromatic poly(amide-imide)s derived from bis(3-trimellitimidophenyl) phenyl phosphine oxide and various aromatic diamines

New aromatic poly(amide-imide)s with high inherent viscosities were prepared by direct polycondensation reaction of diimide-diacid (I) and aromatic diamines using triphenyl phosphite in N-methyl-2-pyrrolidone (NMP)/pyridine solution containing dissolved CaCl2. The bis(3-trimellitimidophenyl) phenyl phosphine oxide (I) was readily obtained by the condensation reaction of bis(3-aminophenyl) phenyl phosphine oxide (BAPPO) with trimellitic anhydride. The resulting poly(amide-imide)s showed high thermostability. Their decomposition temperatures at 10% weight loss in nitrogen atmosphere were above 532 °C and the anaerobic char yield at 800 °C ranged from 56% to 74%. Almost all the poly(amide-imide)s showed high glass transition temperature above 233 °C by differential scanning calorimetry (DSC) measurements. These polymers were readily soluble in various organic solvents and by their casting into transparent, tough and flexible films can be easily achieved.

Photooxygenation of Pregnanes

AbstractThe course of the singlet‐oxygen reaction with pregn‐17(20)‐enes and pregn‐5,17(20)‐dienes was studied to compare the reactivity of the two alkene moieties present in some steroid families. Thus, from commercially available (3β,5α)‐hydroxy‐androstan‐17‐one and (3β)‐3‐hydroxyandrost‐5‐en‐17‐one, the following 3‐{[(tert‐butyl)dimethylsilyl]oxy}‐substituted, 17(20)‐unsaturated pregnanes were prepared (see Fig. 1): (3β,5α)‐21‐norpregn‐17(20)‐ene 1; (3β,5α,17Z)‐pregn‐17(20)‐ene 2, (3β,5α,16α,17E)‐pregn‐17(20)‐en‐16‐ol 3, (16β,5α,17E)‐pregn‐17(20)‐en‐16‐ol 4, (3β,5α,16β,17E)‐pregn‐17(20)‐en‐16‐ol acetate 5, (3β,16α)‐21‐norpregna‐5,17(20)‐dien‐16‐ol 6, (3β,16α,17E)‐pregna‐5,17(20)‐dien‐16‐ol 7, (3β,17Z)‐pregna‐5,17(20)‐diene 8, (3β,17E)‐pregna‐5,17(20)‐dien‐21‐ol 9 and (3β,17E)‐5,17(20)‐dien‐21‐ol acetate 10. The oxygenated products (see Fig. 2) obtained from 1–10 and 1O2, generated by irradiation of Rose Bengal in 3O2‐saturated pyridine solution, were characterized by 1H‐, 13C‐NMR, and MS (EI, FAB, HR‐EI, ESI‐ and UV‐MALDI‐TOF) data. Major products were those formed by the ene reaction involving as intermediates the corresponding hydroperoxides and the cyclic tautomers of the allylic hydroperoxides, i.e., the corresponding oxiranium oxide‐like intermediate (Scheme 5).

Characterization of Pseudopolymorphs of a Hydroxybenzoic Acid Derivative

Hydroxybenzoic acid is used in many applications, including medicine and polymer synthesis. The synthesis, self-assembly, and characterization of three pseudopolymorphs of a derivative of a widely used 4-hydroxybenzoic acid (1) are described in detail. In this investigation, we have incorporated hydrophobic (biphenyl groups) and hydrophilic (-OH and -CO2H) groups on an aromatic ring to influence the self-assembly in the solid lattice. Compound 1 crystallizes into three crystalline forms: (i) monoclinic from a solution of DMSO (1A), (ii) triclinic from a 1:1 solution of DMSO/hot ethyl acetate (1B), and (iii) triclinic from pyridine solution (1C). The formation of these pseudopolymorphs and the structural similarities in their packing motifs can be rationalized through a few multipoint solute−solvent interactions. In all three structures, the crystallographic aspects pertaining to the influence of solvent molecules towards the formation of hydrogen bonded network structures are described. In addition to the strong hydrogen bonds, intermolecular C−H···O, C−H···π, and π···π interactions were found to stabilize the crystal structures.

Reactions of meso-hydroxyhemes with carbon monoxide and reducing agents in search of the elusive species responsible for the g = 2.006 resonance of carbon monoxide-treated heme oxygenase. Isolation of diamagnetic iron(II) complexes of octaethyl-meso-hydroxyporphyrin.

To examine possible models for the g = 2.006 resonance seen when the hydroxylated heme-heme oxygenase complex in the Fe(III) state is treated with CO, the reactivities of CO and reducing agents with (py)(2)Fe(III)(OEPO) and [Fe(III)(OEPO)](2) (OEPO is the trianion of octaethyl-meso-hydroxyporphyrin) have been examined. A pyridine solution of (py)(2)Fe(III)(OEPO) reacts in a matter of minutes with zinc amalgam (or with hydrazine) under an atmosphere of dioxygen-free dinitrogen to produce bright-red (py)(2)Fe(II)(OEPOH).2py.0.33H(2)O, which has been isolated in crystalline form. The (1)H NMR spectrum of (py)(2)Fe(II)(OEPOH) in a pyridine-d(5) solution is indicative of the presence of a diamagnetic compound, and no EPR resonance was observed for this compound. Treatment of a solution of (py)(2)Fe(II)(OEPOH) in pyridine-d(5) with carbon monoxide produces spectral changes after a 30 s exposure that are indicative of the formation of diamagnetic (OC)(py)Fe(II)(OEPOH). Treatment of a green pyridine solution of (py)(2)Fe(III)(OEPO) with carbon monoxide reveals a slow color change to deep red over a 16 h period. Although a resonance at g = 2.006 was observed in the EPR spectrum of the sample during the reaction, the isolated product is EPR silent. The spectroscopic features of the final solution are identical to those of a solution formed by treating (py)(2)Fe(II)(OEPOH) with carbon monoxide. Addition of hydrazine to solutions of (OC)(py)Fe(II)(OEPOH) produces red, diamagnetic (OC)(N(2)H(4))Fe(II)(OEPOH).py in crystalline form. The X-ray crystal structures of (py)(2)Fe(II)(OEPOH).2py.0.33H(2)O and (OC)(N(2)H(4))Fe(II)(OEPOH).py have been determined. Solutions of diamagnetic (OC)(N(2)H(4))Fe(II)(OEPOH).py and (OC)(py)Fe(II)(OEPOH) are extremely air sensitive and are immediately converted in a pyridine solution into paramagnetic (py)(2)Fe(III)(OEPO) in the presence of dioxygen.

Studies with Enaminones: The Reaction of Enaminones with Aminoheterocycles. A Route to Azolopyrimidines, Azolopyridines and Quinolines.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Fluorescence of C60 and Its Interaction with Pyridine

Well-resolved strong fluorescence peaks for C60 dissolved in pyridine in the range from 399 to 750 nm at room temperature are reported. These indicate that C60 has important optical properties and great potential as a new photosensitive and luminescent material. In a C60−pyridine solution, interaction between pyridine and C60, which is further proved by the electroreduction of C60 in pyridine as well as the surface-enhanced Raman scattering (SERS) spectrum of C60, distorts the icosahedral symmetry of C60. The relaxation of selection rules, due to the reduced symmetry of C60 molecule, induces the observed strong fluorescence peaks.

Speciation analysis of organoarsenical compounds in biological matrices by coupling ion chromatography to atomic fluorescence spectrometry with on-line photooxidation and hydride generation

The optimisation of an on-line decomposition based on UV photooxidation for the analysis of organoarsenic species by coupling cation-exchange chromatography and atomic fluorescence spectrometry with hydride generation, is described. In this study, special consideration is given to the compatibility of mobile phases with post-column treatments. Results show that the most commonly used mobile phase, aqueous pyridine solutions, decreases species conversion efficiency, leading to a significant loss of sensitivity. New fully-compatible chromatographic conditions are proposed to separate arsenobetaine, arsenocholine, trimethylarsine oxide and tetramethylarsonium ion within 20min. The very low absolute limits of detection, 4–12pg(As), allow speciation at trace levels. Analysis of a certified reference fish tissue (DORM-2) and other seafood samples (French and Chilean oysters and mussel) highlights the robustness and the accuracy of the optimised system.

Study of Intra- and Intermolecular Interactions with Participation of -Phosphorylated Amines and Alcohols in Different Solvents

Specific interactions of α-hydroxy- and α-aminophosphonates in chloroform and pyridine solutions were studied by theoretical (molecular mechanics) and experimental methods (calorimetry and IR spectroscopy). A competition between intra- and intermolecular interactions and effect of steric factor in molecules of organophosphorus compounds were revealed.