Electrochemical study of (NEt4)2Cl2FeS2MoS2 and (NEt4)2Cl2FeS2MoS2FeCl2

Summary The ability of [MoS₄]^2–, anions to be used as ligands for transition metal ions has been widely demonstrated, especially with Fe²⁺. The present study has been restricted to linear complexes such as (NEt₄)₂ [Cl₂FeS₂MoS₂] and (NEt₄)₂[Cl₂FeS₂MoS₂FeCl₂]. Their electrochemical properties are described: upon electrochemical reduction, these compounds yield MoS₂, as a black precipitate, and an iron complex in solution, assumed to be [SFeCl₂]^2–. The electrochemical reduction goes through two electron transfers, coupled with the breakdown of the molecular skeleton: a DISPl and an ECE mechanism. Depending on the solvent, the following equilibrium may be observed: [Cl₄Fe₂MoS₄]^2–[Cl₂FeMoS₄]^2–+FeCl₂. The equilibrium constant, K_D, was evaluated by differential pulse polarography. K_D is tightly related to the donor number of the solvent.     

Efficient C2 functionalisation of 2H-2-imidazolines

Alkylation and oxidation of 2H-2-imidazolines, followed by regioselective deprotection, thionation and microwave-assisted Liebeskind-Srogl reaction, efficiently led to 2-aryl-2-imidazolines as new analogues of p53-hdm2 interaction inhibitors (Nutlins).     

Syntheses of 2-hydroperoxy-and 2-hydroxy-2H-imidazoles

Oxidation of fully substituted imidazoles 1 by singlet oxygen gives in good yield fully substituted 2-hydroperoxy-2H-imidazoles 2 . Reduction of 2 by triphenylphosphine leads to 2-hydroxy-2H-irnidazoles 3 . Limitations of the methods are reported.     

Homopolymerization of 2-alkyl- and 2-aryl-2-oxazolines

2-Aryl- and 2-alkyl-2-oxazolines have been polymerized to poly-(N-aroyl)aziridines and poly(N-acyl)aziridines, respectively, in the presence of boron trifluoride. The polymers obtained were glassy, light yellow resins with molecular weights ranging from 3500 to 7500 (35–50 oxazoline units per chain). The polymerization rates have been determined for several of these monomers. A polymerization mechanism is proposed.     

Crystal Structures of [Bu2Sn(O2PPh2)2], [Ph2Sn(O2PPh2)2], and [PhClSn(O2PPh2)OMe]2. Raman Spectra of [Ph2Sn(O2PPh2)2] and [PhClSn(O2PPh2)OMe]2

[(n‐Bu)₂Sn(O₂PPh₂)₂] ( 1 ), and [Ph₂Sn(O₂PPh₂)₂] ( 2 ) have been synthesized by the reactions of R₂SnCl₂ (R=n‐Bu, Ph) with HO₂PPh₂ in Methanol. From the reaction of Ph₂SnCl₂ with diphenylphosphinic acid a third product [PhClSn(O₂PPh₂)OMe]₂ ( 3 ) could be isolated. X‐ray diffraction studies show 1 to crystallize in the monoclinic space group P2₁/c with a = 1303.7(1) pm, b = 2286.9(2) pm, c = 1063.1(1) pm, β = 94.383(6)°, and Z = 4. 2 crystallizes triclinic in the space group , the cell parameters being a = 1293.2(2) pm, b = 1478.5(4) pm, c = 1507.2(3) pm, α = 98.86(3)°, β = 109.63(2)°, γ = 114.88(2)°, and Z = 2. Both compounds form arrays of eight‐membered rings (SnOPO)₂ linked at the tin atoms to form chains of infinite length. The dimer 3 consists of a like ring, in which the tin atoms are bridged by methoxo groups. It crystallizes triclinic in space group with a = 946.4(1) pm, b = 963.7(1) pm, c = 1174.2(1) pm, α = 82.495(6)°, β = 66.451(6)°, γ = 74.922(6)°, and Z = 1 for the dimer. The Raman spectra of 2 and 3 are given and discussed.     

Photocycloaddition of 2-Cyanocycloalk-2-Enones to 2, 3-Dimethylbut-2-Ene

Irradiation of 5,5-dimethyl-6-oxocyclohex- l-ene- l-carbonitrile ( 1 ) in the presence of 2,3-dimethylbut-2-ene afforded 3,3,4,4,7,7-hexamethyl-3,4,4a,5,6,7-hexahydroindeno[1,7-c,d]-],2-oxazole (3) in nearly quantitative yield. In contrast, 4,4-dimethyl-5-oxo-cyclopent-l-ene-l-carbonitrile ( 2 ) under the same conditions reacted not to a tricyclic isoxazole but to a 2:1 mixture of 3,3,6,6,7,7-hexamethyl-2-oxo-bicyclo[3.2.0]heptane-l-carbonitrile ( 4 ) and trans-3,3-dimethyl-2-oxo-5-(2,3-dimethylbut-3-en-2-yl)cyclopentane-l-carbonitrile ( 5 ), respectively.     

Ab initio investigation of the potential energy surfaces of C2H2F2 and C2H2F2+

Ab initio MO calculations have been performed for neutral and cationic C₂H₂F₂ structures. Olefinic and carbene structures are investigated for the neutral isomers, while olefinic, carbene, and fluoronium-type cations are found. Stability orders and rotational barriers are discussed in terms of orbital and Coulomb interaction. Contrary to previous studies, the higher stability of the geminal isomers is interpreted to be caused by Coulomb attraction.     

Structure and properties of single crystalline CaMg2Bi2, EuMg2Bi2, and YbMg2Bi2

Single crystals of CaMg(2)Bi(2), EuMg(2)Bi(2), and YbMg(2)Bi(2) were obtained from a Mg-Bi flux cooled to 650 °C. These materials crystallize in the CaAl(2)Si(2) structure-type (P ?3m1, No. 164), and crystal structures are reported from refinements of single crystal and powder X-ray diffraction data. EuMg(2)Bi(2) displays an antiferromagnetic transition near 7 K, which is observed via electrical resistivity, magnetization, and specific heat capacity measurements. Magnetization measurements on YbMg(2)Bi(2) reveal a weak diamagnetic moment consistent with divalent Yb. Despite charge-balanced empirical formulas, all three compounds are p-type conductors with Hall carrier concentrations of 2.0(3) × 10(19) cm(-3) for CaMg(2)Bi(2), 1.7(1) × 10(19) cm(-3) for EuMg(2)Bi(2), and 4.6(7) × 10(19) cm(-3) for YbMg(2)Bi(2), which are independent of temperature to 5 K. The electrical resistivity decreases with decreasing temperature and the resistivity ratios ρ(300 K)/ρ(10 K) ≤ 1.6 in all cases, indicating significant defect scattering.     

Real structure of SrSi2O2N2

SrSi₂O₂N₂ is an important host lattice for Eu²⁺ doped phosphors. Its crystal structure (space group P1, a = 7.0802(2) Å, b = 7.2306(2) Å, c = 7.2554(2) Å, α = 88.767(3)°, β = 84.733(2)°, γ = 75.905(2)° and V = 358.73(2) Å³, Z = 4) is isotypic with EuSi₂O₂N₂: highly condensed silicate layers are separated by Sr²⁺. The samples are characterized by pronounced real structure effects owing to pseudosymmetry of partial structures. Polysynthetic twinning with domains of various sizes is ubiquitous and oriented intergrowth of domains with different orientations has also been observed and analysed in detail by means of electron diffraction and high-resolution electron microscopy. These effects also affect the X-ray powder pattern and were taken into account in a Rietveld refinement.     

Reactions of 2-amino- and 2-hydrazinobenzimidazoles with 2-acyldimedones

The reaction of 2 formyldimedone with 2-amino- and 2-hydrazinobenzimidazoles at 20°C in ethanol gave 2-(2-benzimidazolyl)aminomethylene- and 2-[2-(2-benzimidazolyl)hydrazinomethylene]-5,5-dimethylcylohex-anediones, while this reaction carried out in ethanol at reflux in the presence of acid gave 2,2-dimethyl-4-oxo 1, 2, 3, 4-tetrahydroquinazolino(1, 2-a]benzimidazole and 1-(2-benzimidazolyl)-6, 6-dimethyl-4-oxo-4, S, 6, 7-tetrahydroindazole, respectively.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 247–252, February, 1996.     

Synthesis of fluorodinitromethane and 2-fluoro-2, 2-dinitroethanol

Conclusions The authors have obtained fluorodinitromethane and 2-fluoro-2, 2-dinitroethanol and studied some of their physiocochemical properties.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 912–914, April, 1968.     

Insertion of acetylenes in the PdPd bond of Pd2 (Ph2 PCH2 PPh2)2 Cl2

Dimethylacetylene dicarboxylate and hexafluoro-2-butyne add to Pd₂(dpm)₂Cl₂ (dpm = Ph₂PCH₂PPh₂) to give crystalline adducts Pd₂(dp)₂(μ-acetylene)Cl₂. An X-ray crystal structure of Pd₂(dpm)₂(μ-C₄F₆)Cl₂ reveals that the acetylene has inserted into the metalmetal bond and has been transformed into a cis-dimetallated olefin. The central CC bond length of the bridging olefin is 1.338(16) Å. The coordination about each of the two similar palladium ions is planar and involves two trans-phosphines (one from each of the bridging dpm ligands), a terminal chloride, and one carbon of the bridging olefin. Both Pd₂(dpm)₂Cl₂ and Pd₂(dpm)₂(μ-C₂{CO₂H₃}₂)Cl₂ catalyze the cyclotrimerization of dimethyl-acetylene dicarboxylate.     

Syntheses on the basis of 2H-chromen-2-one and 2H-chromene-2-thione

4-Hydroxy-2H-chromen-2-one and 4-hydroxy-2H-chromene-2-thione reacted with allyl bromide, 1,1,3-trichloroprop-1-ene, and 1,3-dichlorobut-2-ene to give the corresponding ethers, which were oxidized to (2-oxo-2H-chromen-4-yloxy)acetic acid with potassium permanganate, and various derivatives of that acid were obtained. 3-(3,3-Dichloroprop-2-enyl)-7-hydroxy-4-methyl-2H-chromen-2-one and 3-(3,3-dichloroprop-2-enyl)-7-hydroxy-4-methyl-2H-chromene-2-thione were synthesized, and some their transformations were studied.     

Synthesis of 2-deamino- and 2-deamino-2-nitroactinomycin D

A single step synthesis of 2-deaminoactinomycin D ( 3a ) and 2-deamino-2-nitroactinomycin D ( 2a ) arising from actinomycin D ( 1a, AMD ) is reported. Structural confirmation was made by nmr, ir and chemical conversion to known materials.     

Structural chemistry of Ba2CdS3, Ba2CdSe3, BaCdS2, BaCu2S2 and BaCu2Se2

The structures of all compounds were determined from three dimensional single crystal X-ray diffraction data and refined by least squares. Ba₂CdS₃ and Ba₂CdSe₃ are isostructural, Pnma, a = 8.9145(6)Å, b = 4.3356(2)Å, c = 17.2439(9)Å for the former compound and a = 9.2247Å, b = 4,4823(6)Å, c = 17.8706(11)Å for the latter, z = 4, R = 0.0751 and R = 0.0462, respectively. The compounds are isostructural with the previously reported Mn analogues and with K₂AgI₃. Cd ions are in tetrahedral environment and the tetrahedra form infinite linear chains by corner sharing. Ba ions are in 7-fold coordination in which 6 anions form a trigonal prism and 1 anion caps one of the rectangular faces. BaCdS₂, Pnma, a = 7.2781(3)Å, b = 4.1670(1)Å, c = 13.9189(6)Å, z = 4, R = 0.0685. Cd ions can be considered to have a triangular planar coordination with CdS distances of 2.47 and 2.53 Å (twice). Two additional S ions are at 2.89 and 3.22 Å to complete a triangular bipyramidal configuration. Ba is in 7-fold coordination with the anions forming a trigonal prism which is capped on one rectangular face. The compound is isostructural with BaCdO₂ and is related to the structure of BaMnS₂. BaCdSe₂ could not be prepared. BaCu₂S₂ and BaCu₂Se₂ are isostructural, Pnma, a = 9.3081(4)Å, b = 4.0612(3)Å, c = 10.4084(5)Å for the sulfide and a = 9.5944(6)Å, b = 4.2142(4)Å, c = 10.7748(8)Å for the selenide, z = 4, R = 0.0634 and 0.0373, respectively. Ba ions are in the usual 7-fold, capped hexagonal prism, coordination. However, 9 Cu ions also can be considered to form a trigonal prism with all rectangular faces capped, around Ba since the BaCu distances range from 3.24 to 3.54 Å for the sulfide and from 3.37 to 3.67 Å for the selenide. One of the Cu ions is in a very distorted tetrahedral environment and the second one is located in a more regular tetrahedral configuration of the anions. Two independent infinite chains of tetrahedra are present. They are formed by sharing of two adjacent edges of each tetrahedron and then these chains in turn are linked by corner sharing into a three-dimensional network of tetrahedra.     

An Ab Initio Study of C2H2.H2, C2H2.N2, and C2H2.Ar Complexes

Ab initio calculations at the post Hartree–Fock level were performed on complexes of acetylene with hydrogen, nitrogen, and argon. Total energies, optimum geometries, and binding energies were calculated, using the 6-311G** and the 6-31+G(2df,2pd) basis sets. Calculations showed the complexes to be more stable than the separate entities, with the exception of the acetylene–hydrogen complex.