Interlayer inclusion of tetracyanonickelate anion and water molecules: The crystal and molecular structure of [-ZN(en)2-μ-(NC)2-NI-μ -(CN)2-ZN(en) -] n 2n+ ·n[NI(CN)4]2− · 3n H2O

The crystal structure of [Zn(en)₂- (NC)₂Ni(CN)₂ Zn(en)][Ni(CN)₄]· 3 H₂O consists of infinite positively charged wave-shaped layers of composition [Zn(en)₂-(NC)₂Ni(CN)₂- Zn(en)] _n ²ⁿ⁺ with the [Ni(CN)₄]^2– anions and water molecules included between them. Both Ni atoms exhibit square-planar coordination. The chelate bonded en (=ethylenediamine) and N-bonded cyano ligands around two independent zinc atoms form a deformed tetrahedron and a deformed octahedron, respectively. Yellow needles of the complex belong to the orthorhombic space groupPbcm witha = 6.977(1),b = 25.407(4),c = 14.876(2)Å,Z = 4,D _m = 1.74(1) g cm^–3 andD _c = 1.739 g cm^–3. The structure was refined toR = 6.31 %.     

NEW THREE DIMENSIONAL [Cd(CN)2]n FRAMEWORK FORMED WITH CADMIUM CYANIDE AND Cd(CN)2·(18-CROWN-6): CRYSTAL STRUCTURE OF [Cd(CN)2]·1/2[Cd(CN)2 (18-CROWN-6)]·3/2EtOH+

Abstract

The cadmium complex Cd(CN)₂·(18-crown-6) (1) was synthesized and its structure was determined by X-ray crystallography. The cadmium ion in 1 has a hexagonal bipyramidal geometry containing six equatorial oxygen atoms from the crown ether and two axial CN ligands. The NC-Cd-CN ‘rod’ is perfectly linear with an end-to-end distance of 6.509 (12) Å. When 1 was allowed to diffuse into a cadmium cyanide solution, the infinite coordination complex [Cd(CN)₂]·1/2[(Cd(CN)₂·(18-crown-6)]·3/2EtOH (2) was obtained in which the cadmium macrocycle 1 was trapped in a 10-faced-cage formed by the [Cd(CN)₂]n framework. The terminal nitrogen atoms of 1 bind two Cd centers across the cage. The trapped Cd(CN)₂·(18-crown-6) has a significantly bent NC-Cd-CN unit and the crown ether ligand disordered over two orientations. The [Cd(CN)₂]_n framework viewed down the c axis shows two types of channels, one octagonal and one tetragonal, which are filled with Cd(CN)₂·(18-crown-6) and ethanol molecules, respectively. Crystallographic data of 1: trigonal, space group R·3 (hexagonal axis), a = 11.757 (1), c = 12.105 (1) Å, V = 1449.1 (2) ų, Z = 3, R = 0.0566, R_w = 0.0674 for 827 unique reflections (I>3σ(I)). Crystallographic data of 2: orthorhombic, Pbcn, a = 16.632 (1), b = 17.391 (3), c = 15.685 (2) Å, V = 4536.8 (9) ų, Z = 8. R = 0.0486, R_w = 0.0492 for 929 unique reflections (I>3σ(I)).     

Structures of Pd(CN)2 and Pt(CN)2: intrinsically nanocrystalline materials?

Analysis and modeling of X-ray and neutron Bragg and total diffraction data show that the compounds referred to in the literature as "Pd(CN)(2)" and "Pt(CN)(2)" are nanocrystalline materials containing small sheets of vertex-sharing square-planar M(CN)(4) units, layered in a disordered manner with an intersheet separation of ~3.44 ? at 300 K. The small size of the crystallites means that the sheets' edges form a significant fraction of each material. The Pd(CN)(2) nanocrystallites studied using total neutron diffraction are terminated by water and the Pt(CN)(2) nanocrystallites by ammonia, in place of half of the terminal cyanide groups, thus maintaining charge neutrality. The neutron samples contain sheets of approximate dimensions 30 ? × 30 ?. For sheets of the size we describe, our structural models predict compositions of Pd(CN)(2)·xH(2)O and Pt(CN)(2)·yNH(3) (x ≈ y ≈ 0.29). These values are in good agreement with those obtained from total neutron diffraction and thermal analysis, and are also supported by infrared and Raman spectroscopy measurements. It is also possible to prepare related compounds Pd(CN)(2)·pNH(3) and Pt(CN)(2)·qH(2)O, in which the terminating groups are exchanged. Additional samples showing sheet sizes in the range ~10 ? × 10 ? (y ~ 0.67) to ~80 ? × 80 ? (p = q ~ 0.12), as determined by X-ray diffraction, have been prepared. The related mixed-metal phase, Pd(1/2)Pt(1/2)(CN)(2)·qH(2)O (q ~ 0.50), is also nanocrystalline (sheet size ~15 ? × 15 ?). In all cases, the interiors of the sheets are isostructural with those found in Ni(CN)(2). Removal of the final traces of water or ammonia by heating results in decomposition of the compounds to Pd and Pt metal, or in the case of the mixed-metal cyanide, the alloy, Pd(1/2)Pt(1/2), making it impossible to prepare the simple cyanides, Pd(CN)(2), Pt(CN)(2), or Pd(1/2)Pt(1/2)(CN)(2), by this method.     

Syntheses and Crystal Structures of Two Ion Pair Complexes, [Ru(bpy)3]2[Fe(CN)6]I · 7H2O and [Ru(bpy)3]- [Fe(CN)5NO]CH3OH · H2O

Two ion pair complexes, [Ru(bpy)₃]₂[Fe(CN)₆]I [sdot] 7H₃O (1) and [Ru(bpy)₃][Fe(CN)₅NO](CH₃OH) [sdot] H₂O (2) (bpy = 2,2-bipyridine) have been synthesized and structurally characterized. X-Ray crystallographic structures of 1 and 2 both show Fe(III) and Ru(II) in distorted octahedral environments. In both complexes, H-bonding interactions between an uncoordinated water molecule and the nitrogen atom of a cyano group exist.     

Syntheses and crystal structures of oxovanadium(V) complexes derived from N′-[1-(2-hydroxynaphthyl)ethylidene]-4-nitrobenzohydrazide and 2-hydroxy-N′-[1-(2-hydroxynaphthyl)ethylidene]benzohydrazide

Reactions of bis(acetylacetonato)oxovanadium(IV) with N??-[1-(2-hydroxynaphthyl)ethylidene]-4-nitrobenzohydrazide (H₂HNB) and 2-hydroxy-N??-[1-(2-hydroxynaphthyl)ethylidene]benzohydrazide (H₂HHB), respectively, product two oxovanadium(V) species with the formulas [VO(OMe)(HNB)]₂ (I) and [VO(OMe)(HHB)] (II). The complexes I and II have been characterized by elemental analysis, IR spectra, and single crystal X-ray diffraction. The crystal of I is monoclinic: space group P2₁/n, a = 8.208(2), b = 14.528(3), c = 16.418(3) ?, ?? = 97.887(3)°, V = 1939.3(7) ?³, Z = 2. The crystal of II is triclinic: space group P $P\bar 1$ a = 8.334(2), b = 10.236(2), c = 11.337(2) ?, ?? = 80.91(3)°, ?? = 75.41(3)°, ?? = 75.63(3)°, V = 902.0(3) ?³, Z = 2. Complex I is a methoxide-bridged dimeric oxovanadium(V) complex, and complex II is a mononuclear oxovanadium(V) complex. The V atom in I is in an octahedral coordination, and that in II is in a square pyramidal coordination.     

Synthesis and Structure of Acetonitrile Solvates of Copper(II) Monofluoroacetate and Silver(I) Trifluoroacetate, [Cu2(CH2FCOO)4· 2CH3CN](CH3CN) and Ag3(CF3COO)3(CH3CN)2

Compounds [Cu₂(CH₂FCOO)₄· 2CH₃CN](CH₃CN) (I) and Ag₃(CF₃COO)₃(CH₃CN)₂(II) were synthesized and studied by X-ray structural analysis. Crystals Iare monoclinic, space group C2/c, a= 27.854(6), b= 8.286(2), c= 19.428(4) Å, = 106.82(3)°, V= 4292(2) ų, Z= 8, R ₁= 0.0426; crystals IIare triclinic, space group , a= 8.676(2), b= 9.819(2), c= 11.961(2) Å, = 95.27(3), = 109.59(3)°, = 104.60(3)°, V= 911.4(3) ų, Z= 2, R ₁= 0.0252. Structure Iis composed of the structural units (lanterns) typical of copper(II) carboxylates. The presence of an additional acetonitrile molecule noncoordinated by the copper atoms makes it possible to consider compound Ias a lattice clathrate. Structure IIhas no analogs among the silver carboxylates. It simultaneously contains silver atoms with coordination numbers varying from 2 to 4.     

Syntheses,molecular structures,and antiviral activities of 1- and 2-(2′-deoxy-d-ribofuranosyl)cyclohepta[d][1,2,3]triazol-6(1H)-ones and 1-(2′-deoxy-d-ribofuranosyl)cyclohepta[b]pyrrol-8(1H)-one

The synthesis of a novel class of 2′-deoxyribonucleosides possessing tropone-fused nitrogen heterocycles as nucleobases was developed. The reaction of alkali metal salts of 1H-cyclohepta[d][1,2,3]triazol-6-one with 2-deoxy-3,5-di-O-(p-toluoyl)-α-d-ribofuranosyl chloride (α-chlorosugar) afforded an anomeric mixture of N1- and N2-coupled glycosylation products. Good stereospecificity in relation to the amount of the β-anomer was achieved in the less polar solvent DME. The reactions of the sodium salt of 1H-cyclohepta[b]pyrrol-8-one and its 3-methyl derivative with an α-chlorosugar in DME gave the β-anomer of the N1-coupled glycosylation products. The glycosylation products were treated with NaOMe in MeOH to produce the desired 2′-deoxyribonucleosides. X-ray structural analyses of the three nucleosides prepared confirmed their anomeric configuration and revealed that their sugars were puckered. The β-anomers of the nucleosides had weak antiviral activities for herpes simplex virus type 1 and herpes simplex virus type 2 in comparison with those of acyclovir (ACV). These nucleosides showed no cytotoxicity on a lung (A549) and two colon (HT-29 and HCT-116) cancer cell lines.     

Evidence for hydrogen bond network formation in microsolvated clusters of Pt(CN)4(2-): collision induced dissociation studies of Pt(CN)4(2-)·(H2O)(n) n = 1-4, and Pt(CN)4(2-)·(MeCN)(m) m = 1, 2 cluster ions

Low-energy collision induced dissociation has been used to investigate the structure and stability of microsolvated clusters of the prototypical, aprotic multiply charged anion, Pt(CN)(4)(2-), i.e. Pt(CN)(4)(2-)·(H(2)O)(n) n = 1-4, Pt(CN)(4)(2-)·(MeCN)(m) m =1, 2, and Pt(CN)(4)(2-)·(H(2)O)(3)·MeCN. For all of the systems studied, the lowest energy fragmentation pathway was found to correspond to decay of the cluster with loss of the entire solvent ensemble. No sequential solvent evaporation was observed. These observations suggest that the Pt(CN)(4)(2-) solvent clusters studied here form hydrogen-bonded "surface solvated" structures. Electronic structure calculations are presented to support the experimental results. In addition, the detailed fragmentation patterns observed are interpreted with reference to the differential solvation of the ionic fragmentation and electron detachment potential energy surfaces of the core Pt(CN)(4)(2-) dianion. The results described represent some of the first experiments to probe the microsolvation of this important class of multiply charged anions.     

Syntheses,characterisation and solid state thermal studies of 1-(2-aminoethyl)piperidine (L), 1-(2-aminoethyl)pyrrolidine (L′) and 4-(2-aminoethyl)morpholine (L″) complexes of nickel(II): X-ray single crystal structure analyses of trans-[NiL2(CH3CN)2](ClO4)2, trans-[NiL2(NCS)2] and trans-[NiL″2(NCS)2]

Reactions of nickel(II) salts with substituted ethane-1,2-diamine where one of the amine nitrogens is a part of a flexible cyclic ring, e.g. 1-(2-aminoethyl)piperidine (L), 1-(2-aminoethyl)pyrrolidine (L′) and 4-(2-aminoethyl)morpholine (L″) produce a number of complexes of the type: (i) Ni(AA)₂X₂ (where X=CF₃CO₂ ⁻, SCN⁻ and NO₂ ⁻; AA represents L/L′/L″); (ii) Ni(AA)₂(CH₃CN)₂X₂ (X=ClO₄ ⁻ and NO₃ ⁻); (iii) Ni(AA)₂(H₂O)₂X₂ (X=CF₃SO₃ ⁻, Cl⁻, Br⁻ and I⁻); and (iv) Ni(AA)₂(H₂O)₄X₂ (X=0.5SO₄ ²⁻, 0.5SeO₄ ²⁻ and CF₃SO₃ ⁻). The complexes possess octahedral geometry. The major complexes upon desolvation retain trans-geometry, some of which are cis with respect to the counter-anion and a few of them are square planar. X-ray single crystal structure analyses of trans-[NiL₂(CH₃CN)₂](ClO₄)₂, trans-[NiL₂(NCS)₂] (violet) and trans-[NiL″₂(NCS)₂] (sky-blue) have been done. The violet and sky-blue thiocyanato species have blue and green coloured isomers, respectively, and these pairs of isomers are proposed to be conformational isomers. Solid state thermal investigation of the complexes has been carried out. The complexes show thermochromism due to deaquation–anation/deaquation reaction/change of conformation. Only [NiL₂](ClO₄)₂, [NiL′₂(CF₃CO₂)₂] and [NiL″₂(NO₂)₂] undergo thermally induced phase transition. The effect of flexible ring size on diamine has been discussed.     

Synthesis and Crystal Structure of (E)-[1-Ferrocenyl-2-(4-Chlorophenyl) ethylene]

1INTRoDUCTIoNCurrently,thereisaconsiderableinterestintheinvestigationoforganicandorganometallicmaterialsshowinglargenonlinearopticalresponse.Theirpotentialusehasbeenresearchedindeviceapplicationswhicharerelatedtothetelecommuni-cations,opticalcomputingandopticalinformationprocessing"2i.Onamicroscopiclevel,oneofthemajorphysicalparameterstodecidethenonlinearopticalpropertiesofmaterialsisthemolecularhyperpolarizability,avaluedeterminedbyelectronicandgeometricstructureofmolecule.Thetitlecompoun…     

Synthesis, properties, and thermal decomposition of compounds [Co(En)3][Fe(CN)6] · 2H2O and [Co(En)3]4[Fe(CN)6]3 · 15H2O

Binary complex salts, [Co(En)₃][Fe(CN)6] · 2H₂O and [Co(En)₃]₄[Fe(CN)₆]₃ · 15H₂O, are synthesized. The properties of the salts and their thermolysis in air, dihydrogen, and argon are studied. Oxides of the central ions of the binary complex salts are found to be the thermolysis products in an oxidative atmosphere. Solid solutions (intermetallic compounds) CoFe are the thermolysis products in the reductive atmosphere, whereas intermetallides containing considerable amounts of C and N and an impurity of Co and Fe oxides are the thermolysis products in an inert atmosphere. Gaseous thermolysis products in dihydrogen and argon are NH₃, hydrocarbons, and ethylenediamine.     

Synthesis and Crystal Structure of an Ion-Pair Compound:[HL]2[Ni(CN)4]·4H2O(L=4-(2-Hydroxyphenyl)-1,5,9-triazacyclododecan-2-one)

An ion-pair compound,[HL]2[Ni(CN)4]·4H2O 1 has been obtained as an unexpected product when we attempt to prepare a heterometallic cyano-bridged complex by the reaction of GdCl3·nH2O,K2Ni(CN)4 and L (L=4-(2-hydroxyphenyl)-1,5,9-triazacyclododecan-2-one) in aqueous solution,and characterized by single-crystal X-ray diffraction.It crystallizes in monoclinic,space group P21/n with a=12.380(1),b=9.9637(8),c=17.087(1)A,β=105.947(2)°,V=2026.6(3) A3,Rint=0.0509,Z=2,Dc=1.297g/cm3,C34H56O8N10Ni,Mr=791.60,F(000)=844,μ(MoKα)=0.538 mm-1,S=1.030,the final R=0.0644 and wR=0.1299 for 2023 observed reflections with I≥2σ(I).The title compound 1 contains one anion of [Ni(CN)4]2-,two cations of [HL]+and four packing water molecules,which are held together by the N-H…O and O-H…O hydrogen bonds to form a three-dimensional framework.     

Crystal Structure and Conformation of [1-(β-D-lyxofuranosyl)uracil]- 2''''-spiro-5"-[4"-(S)-(diethoxyphosphinyl)-2"-oxazoline]

1 INTRODUCTION It is well known that natural and modified nucleosides have potential antiviral and anticancer activities[1,2]. These observations prompted us to synthesize the title compound －a new kind of spironucleoside, whose structure was determined by 1HNMR, 31PNMR and elemental analysis. The configuration was assigned by means of nuclear Overhauser effect. To further confirm the structure and configuration unambiguously, the title compound was subjected to X-ray diffractio…     

Iron salts with the tetracyanidoborate anion: [Fe(III)(H2O)6][B(CN)4]3, coordination polymer [Fe(II)(H2O)2{κ2N[B(CN)4]}2], and [Fe(II)(DMF)6][B(CN)4]2

The reaction of Fe(OH)(3) with tetracyanidoboronic acid, H[B(CN)(4)]·xH(2)O, in water leads to the first examples of tetracyanidoborates with a triply charged metal cation, [Fe(III)(H(2)O)(6)][B(CN)(4)](3) (1). Using elemental iron powder as starting material, [Fe(II)(H(2)O)(2){κ(2)ΝB(CN)(4)]}(2)] (2) is obtained. Anhydrous iron(II) tetracyanidoborate, which is synthesized by heating of 2, is soluble in dry dimethylformamide. After evaporation of the DMF solvent, single crystals of the third title compound, [Fe(II)(DMF)(6)][B(CN)(4)](2) (3), are obtained. Compound 3 is the first metal tetracyanidoborate soluble in nonpolar solvents. The title compounds have been characterized by single-crystal X-ray diffraction (1 rhombohedral, R3c (no. 167), a = 14.9017(7) ?, c = 20.486(1) ?, Z = 6; 2 tetragonal, I42d (no. 122), a = 12.3662(3) ?, c = 9.2066(4) ?, Z = 4; 3 triclinic, P1 (no. 2), a = 8.6255(3) ?, b = 11.0544(4) ?, c = 12.2377(5) ?, Z = 1). The metal ions in all three compounds are octahedrally coordinated. Whereas 1 and 3 are built up from isolated complex ions, 2 comprises a coordination polymer, in which the Fe(II) ion is coordinated by two oxygen atoms of two water molecules in a trans orientation and four nitrogen donor atoms of the [B(CN)(4)](-) groups, which bridge between neighboring iron ions. The iron(III) ion in 3 is in a perfect octahedral environment, which is formed by the O atoms of 6 molecules of water. The single-crystal X-ray structures, vibrational spectra, thermal properties, solubilities, and electrochemical characteristics are reported and compared with those of other known tetracyanidoborates.     

Synthesis of 1-[6-Fluoro-(2S)-3H,4H-dihydro-2H-2-chromenyl]-(1R)-1,2- ethanediol and 1-[6-Fluoro-(2R)-3H,4H-dihydro-2H-2-chromenyl]- (1R)-1,2-ethanediol

Benzopyran compounds possess diverse pharmacological properties such as β-blockade, anticonvulsant and antimicrobial.[1,2] Our interest has been focused on the synthesis of 1-[6-Fluoro-2S]-3H,4H-dihydro-2H-2-chromenyl]-(1R)-1,2-ethanediol (6) and 1-[6-fluoro-(2R)-3H,4H-dihydro-2H-2-chromenyl]-(1R)-1,2-ethanediol (7) which are particularly convenient precursor to (S,R,R,R)-NE (8). 8 containing four asymmetrical carbon atoms was reported to be the most active isomer.[3] Chandrasekhar[4] has reported on the synthesis of 8. The key step to synthesize this compound is to obtain the chiral chromanone 6 and 7. 6 was accomplished in 8 steps by the Clasien rearrangement and a one-pot Sharpless asymmetric epoxidation, but the compound 7 was accomplished in 10 steps. Johannes[5] used Zr-catalytic kinetic resolution of allylic ethers and Mo-catalyzed chromene formation to synthesize 8 in 14 steps. However both of the methods request many synthetic steps and expensive reagents.     

Synthesis,halogenation and structural characterization of (Z)-1-[2-(triphenylstannyl)vinyl]-l-cyclododecanol

Synthesis and characterization of (Z)-1-[2-(triphenylstannyl)vinylj-l-cyclododecanol,c-(CH2)11C(OH)CH=CHSnPh3,are reported,together with its halogenation by I2,Br2 and IC1 to yield derivatives of the types c-(CH2)11C(OH)CH=CHSnPh3_nXn (n=1,2; X=I,Br,Cl,respectively).The molecular structures of two compounds have been determined by X-ray diffraction analysis.The tin atom exhibits a distorted tetrahedral geometry in the crystal of (Z)-1-[2-(triphenylstannyl)vinyl]-1-cyclododecanol,but a trigonal bipyramidal geometry in the monoiodo-derivative (Z)-1-[2-(diphenyliodo-stannyl)vinyl]-l-cyclododecanol and other derivatives,in which significant intramolecular coordinative interaction HO→Sn is observed.And the formation of a five-membered tin containing ring is significant for their antitumour activities.     

Interpretation der Absorptionsspektren der Komplexionen [Mo(CN)8]4−, [Mo(CN)8]3−, [W(CN)8]4− und [W(CN)8]3−

Zusammenfassung Die Absorptions- und Reflexionsspektren der Oktocyanokomplexe desMo(IV) undW(IV) sowie die Absorptionsspektren der Oktocyanotomplexe desMo(V) undW(V) werden mitgeteilt. Die Spektren werden unter Zugrundelegung der durch Raman- und IR-spektroskopische Untersuchungen gefordertenD _4d-Symmetrie dieser Verbindungen interpretiert. Die beobachteten Banden niedriger Intensität (log<3) werden Übergängen in einem Termsystem zugeordnet, das für die Konfigurationend ² undd ₁ und die SymmetrieD _4d berechnet worden ist. Banden hoher Intensität (log>3) werden auf Übergänge in antibindende Zustände zurückgeführt, an denen höherep-Zustände des Zentralions sowie Ligandenzustände beteiligt sind. Die erhaltenen Werte des Feldparameters stimmen mit ligandenfeldtheoretischen Erwartungen überein.

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Absorption and reflection spectra of the octacyanides ofMo(IV) andW(IV) and the absorption spectra of the octacyanides ofMo(V) andW(V) are presented. The spectra are interpreted in terms of theD _4d symmetry of the compounds supported by investigations of Raman and infrared spectra. Bands of low intensity (log<3) correspond to transitions between levels obtained in the case of the configurationsd ² andd ¹ respectively, in a field ofD _4d symmetry. Bands of high intensity (log>3) are attributed to transitions into antibonding levels in which p-orbitals of the central ion and ligand orbitals participate. The values of the field parameter obtained are in accord with ligand field theory.

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Résumé Les spectres d'absorption et de réflexion des complexes octocyanurés duMo(IV) et duW(IV) ainsi que les spectres d'absorption des mêmes complexes deMo(V) et de W(V) sont présentés. Les spectres sont interprétés en supposant la symétrieD _4d des molécules indiquée par des analyses des spectres Raman et infrarouges. Les bandes de faible intensité (log<3) sont attribuées à des transitions dans un système de niveaux, calculé pour les configurationsd ² etd ¹, respectivement, en symétrieD _4d. Des bandes de forte intensité (log>3) sont attribuées à des transitions vers des niveaux antiliants auxquels participent des fonctions élevéesp de l'ion central et des fonctions des groupes liés. Les valeurs obtenues pour le paramètre de champ sont en accord avec les prévisions de la théorie.

     

Crystal Structure and Conformation of [1-(β-D-lyxofuranosyl)uracil]-2′-spiro-5″-[4″-(S)-(diethoxyphosphinyl)-2″-oxazoline]

The title compound, C15H22N3O9P·2H2O, Mr=455.36, crystallizes in orthorhombic, space group P212121, with a =9.193(2), b =14.681(3), c =15.201(3)A, V =2501(1)A3, Z =4, Dx=1.474g/cm3, λ(MoKα)=0.71073A, μ=0.1894mm-1, T=299±1K, F(000)=960, R=0.061 and Rw=0.068 for 1899 observed reflections with I≥3σ(I). The analysis results indicate that the title compound is of lyxo-configuration and the configuration at C4″ is S. In the crystal state the molecule has anti conformation about glycosidic bond with the torsion angle-151.7°, the sugar ring is puckered with C3′-endo-C2′-exo, and the conformation of the C4′-C5′ bond is-sc.     

Efficient synthesis and resolution of (±)-1-[2-carboxy-6-(trifluoromethyl)phenyl]pyrrole-2-carboxylic acid

A novel, efficient synthesis and resolution of (±)-1-[2-carboxy-6-(trifluoromethyl)-phenyl]pyrrole-2-carboxylic acid has been developed for the preparation of new members of optically active atropisomers. The e.e. values were determined by a highly sensitive ¹⁹F NMR spectroscopic method using β-cyclodextrin as chiral complexing agent. Single-crystal X-ray structures of the two diastereoisomeric salts and consequently, the absolute configurations of the enantiomers are also reported.     

Synthesis and some transformations of trans-1-methyl-2-[β-(2′-thienyl)vinylene]-1H-benzimidazole

The condensation of 1,2-dimethylbenzimidazole with thiophene-2-aldehyde in the presence of fused zinc chloride results in 1-methyl-2-[β-(2-thienyl)vinylene]-1H-benzimidazole. Its electrophilic substitution reactions (nitration, bromination, sulfonation, formylation, acylation) were studied. All the reactions occur in the 5-position of the thiophene ring. Only in the case of bromination in dichloroethane 5′,5(6)-dibromo-derivative was obtained. Data of the quantum-chemical calculations of the total positive charge on the carbon atoms of the protonated molecules of thienylbenzimidazoles including the vinylene group and without it are reported.