Photoelectric properties of In/CdP2 surface barrier structures

We used vapor-phase crystallization to grow homogeneous single crystals of the compound CdP₂ of diameter 20 mm and length up to 50 mm. We determined the unit cell parameters and the composition of the single crystals grown. We created photosensitive In/CdP₂ surface barrier structures and studied their photosensitivity spectra. Based on these studies, we established the broadband character of the photosensitivity of the structures, the nature of the photoconversion processes, and the type of interband transitions. We conclude that it is possible to use CdP2 single crystals as broadband photoconverters for natural light.     

Amidoximes provide facile platinum(II)-mediated oxime-nitrile coupling

The nucleophilic addition of amidoximes R'C(NH(2))═NOH [R' = Me (2.Me), Ph (2.Ph)] to coordinated nitriles in the platinum(II) complexes trans-[PtCl(2)(RCN)(2)] [R = Et (1t.Et), Ph (1t.Ph), NMe(2) (1t.NMe(2))] and cis-[PtCl(2)(RCN)(2)] [R = Et (1c.Et), Ph (1c.Ph), NMe(2) (1c.NMe(2))] proceeds in a 1:1 molar ratio and leads to the monoaddition products trans-[PtCl(RCN){HN═C(R)ONC(R')NH(2)}]Cl [R = NMe(2); R' = Me ([3a]Cl), Ph ([3b]Cl)], cis-[PtCl(2){HN═C(R)ONC(R')NH(2)}] [R = NMe(2); R' = Me (4a), Ph (4b)], and trans/cis-[PtCl(2)(RCN){HN═C(R)ONC(R')NH(2)}] [R = Et; R' = Me (5a, 6a), Ph (5b, 6b); R = Ph; R' = Me (5c, 6c), Ph (5d, 6d), correspondingly]. If the nucleophilic addition proceeds in a 2:1 molar ratio, the reaction gives the bisaddition species trans/cis-[Pt{HN═C(R)ONC(R')NH(2)}(2)]Cl(2) [R = NMe(2); R' = Me ([7a]Cl(2), [8a]Cl(2)), Ph ([7b]Cl(2), [8b]Cl(2))] and trans/cis-[PtCl(2){HN═C(R)ONC(R')NH(2)}(2)] [R = Et; R' = Me (10a), Ph (9b, 10b); R = Ph; R' = Me (9c, 10c), Ph (9d, 10d), respectively]. The reaction of 1 equiv of the corresponding amidoxime and each of [3a]Cl, [3b]Cl, 5b-5d, and 6a-6d leads to [7a]Cl(2), [7b]Cl(2), 9b-9d, and 10a-10d. Open-chain bisaddition species 9b-9d and 10a-10d were transformed to corresponding chelated bisaddition complexes [7d](2+)-[7f](2+) and [8c](2+)-[8f](2+) by the addition of 2 equiv AgNO(3). All of the complexes synthesized bear nitrogen-bound O-iminoacylated amidoxime groups. The obtained complexes were characterized by elemental analyses, high-resolution ESI-MS, IR, and (1)H NMR techniques, while 4a, 4b, 5b, 6d, [7b](Cl)(2), [7d](SO(3)CF(3))(2), [8b](Cl)(2), [8f](NO(3))(2), 9b, and 10b were also characterized by single-crystal X-ray diffraction.     

Transition-Metal-Free Superbase-Promoted Stereoselective α-Vinylation of Ketones with Arylacetylenes: A General Strategy for Synthesis of β,γ-Unsaturated Ketones

A wide variety of β,γ-unsaturated ketones of E configuration have been obtained in good to excellent yields via KO(t)Bu/DMSO promoted α-vinylation of aliphatic, cycloaliphatic, and alkyl aromatic (heteroaromatic) ketones with diverse arylacetylenes.     

Conversion of low spin states in a monochelate complex of Fe(III) with an asymmetric tridentate azomethine ligand

An iron(III)-containing complex with the asymmetric tridentate azomethine ligand 4,4′-dodecyloxybenzoyloxybenzoyl-4-salicylidene-N′-ethyl-N-ethylenediamine with a PF ₆ ^? counterion is obtained. The presence of the complexing ion is confirmed by far IR Fourier spectra. The structure of the compounds is determined by matrix-assisted laser desorption/ionization with a time-of-flight mass analyzer (MALDI-ToF). The results of mass spectrometric studies are consistent with the elemental analysis data. It is found that the complexation of iron salt with an asymmetric tridentate ligand results in the formation of compounds of the composition 1:1 with octahedral packing of a metal ion in the complex. The electrochemical behavior of the compound in organic solvents is examined. The EPR study shows that iron(III) ions are in both low spin (LS) and high spin (HS) states in the complex. The LS and HS iron(III) centers are coupled into dimers in which a water molecule and the PF ₆ ^? counterion act as bridges. It is also found that for LS complexes in the lowtemperature phase (4.2–300 K), the (d _xz ,d _yz )⁴(d _xy )¹ electronic state is the ground state. It is revealed that the conversion of the sample into a high-temperature liquid crystalline (387–405 K) phase is accompanied by the conversion of the LS states of the Fe(III) ion: (d _xz ,d _yz )⁴(d _xy )¹ ? (d _xy )²(d _xz ,d _yz )³. The conversion of LS states is temperature reversible and is driven by the temperature. X-ray crystallographic data confirm that the compound obtained consists of dimer formed by a hydrogen (O-H...F) bond.     

Synthesis of CF3-containing tetrapeptide surrogates via Ugi reaction/dipolar cycloaddition sequence

A convenient synthetic pathway to novel functionalized tetrapeptides containing the 1,2,3-triazole moiety is described. The target molecules were obtained by the reaction of fluorinated α-amino acids or α-aminophosphonates with azidopeptides via Cu(I)-catalyzed Huisgen cycloaddition reaction (click chemistry). The synthesized tetrapeptides may find important applications in biomedical chemistry as potential drugs.     

A peculiar transition-metal-free cyclodimerization of propargylic alcohols to vinyl bicyclic ketals

Propargylic alcohols, alkylaryl(hetaryl)ethynyl carbinols, under transition-metal-free conditions (KOH/DMSO, 70–80 °C, 10–15 min) unexpectedly undergo stereoselective cyclodimerization to 7-methylene-6,8-dioxabicyclo[3.2.1]octanes having the scaffold of known insect pheromones and marine toxins. Under acetylenic pressure the yields of bicyclic ketals reach 80%. In all the cases, the cyclodimers are formed exclusively as one diastereomer.     

Kinetics and mechanism of the hydration of the equilibrium mixture of 3-methyl-1-buten-3-ol and 3-methyl-2-buten-1-ol with isoprene in aqueous solutions of sulfuric acid

The kinetic relationships of the hydration of an equilibrium mixture of 3-methyl-1-buten-3-ol (dimethylvinylcarbinol, DMVC) and 3-methyl-2-buten-1-ol (dimethylallyl alcohol, DMAA) with isoprene (C₅H₈) were investigated in aqueous solutions of sulfuric acid from 24.9 to 49.7% at 25°C. Data were obtained on the mechanism of hydration of the equilibrium mixture of DMVC and DMAA with isoprene.Deceased.N. N. Semenov Institute of Chemical Physics, Russian Academy of Sciences, 117977 Moscow. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 6, pp. 1311–1314, June, 1992.     

Propane dehydrogenation by SO2 in the presence of carbon

The oxidative condensation products of the title reaction are catalytically active, presumably because sulfur enters into their composition.

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Structure of 1,4,10,19,25,41-C70(CF3)6, isomer with unique arrangement of addends

A novel isomer of C₇₀(CF₃)₆ has been isolated by HPLC from a mixture prepared by trifluoromethylation of C₇₀ with CF₃COOAg. The X-ray structure revealed an unprecedented arrangement of CF₃ groups forming a p³mp ribbon. This result provides additional evidence of the preferable formation of trifluoromethylated fullerene molecules comprising a single continuous ribbon of edge-sharing para- and meta-C₆(CF₃)₂ hexagons.