Half-sandwich complexes of lanthanides with tridentate ligands [RCH2CH(O)CH2OBun]2– (R = C5H4, 1-C9H6): synthesis,structures, and properties. The crystal structure of the complex {[(η5-C5H4)CH2CH(μ2:η1-O)CH2OBun]LaN(SiMe3)2}2

The oxirane-ring opening of butyl glycidyl ether with cyclopentadienylsodium or indenylsodium afforded cyclopentadienyl- and indenyl-substituted alcohols RHCH₂CH(OH)CH₂OBuⁿ (R = C₅H₄ (1) or 3-C₉H₆ (2), respectively), which were used as tridentate ligands. The reactions of these compounds with Ln[N(SiMe₃)₂]₃ produced the lanthanide complexes {[(⁵-R)CH₂CH(²:¹-O)CH₂OBuⁿ]LnN(SiMe₃)₂}₂ (R = C₅H₄, Ln = La (3), Pr (4), Er (5), Lu (6); or R = 1-C₉H₆, Ln = La (7)). The coordination spheres of the metal atoms in these complexes involve simultaneously the ⁵-cyclopentadienyl (indenyl), bridging alkoxide, and terminal amide ligands. The complexes were characterized by microanalysis, IR and NMR spectroscopy, and magnetochemistry. The crystal and molecular structure of complex 3 was established by single-crystal X-ray diffraction analysis.     

Effect of oxygen pressure on phase equilibria in the Eu-Mn-O system

Phase equilibria in the Eu-Mn-O system are studied using the static method in combination with X-ray phase analysis. Compound EuMnO₃ was studied by means of DSC and high-temperature roentgenography. The transformation of the orbitally ordered O′ phase to the orbitally disordered O phase was confirmed for the EuMnO₃ compound. Thermodynamic characteristics of the formation of EuMn₂O₅ and EuMnO₃ compound from their elements were calculated.     

Comparative evaluation of antioxidant activity of 2-alkyl-4-methylphenols and their 6-n-octylaminomethyl derivatives

Russian Chemical Bulletin - A series of 2-alkyl-4-methyl-6-n-octylaminomethylphenols (where alkyl is methyl or tert-butyl group, or terpene substituent) was synthesized. A comparative evaluation of...     

Macrocycle opening in formyl derivatives of benzocrown ethers under the action of methylamine

A new method for synthesizing nitrogen-containing podands by nucleophilic regioselective cleavage of the macrocycle in formyl derivatives of benzocrown ethers by heating with methylamine and methylammonium chloride has been developed. This reaction is the first example of crown ether opening by a nitrogen-containing nucleophile.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 950–953, May, 1995.     

Synthesis of crown-containing 2-styrylbenzothiazoles. Effect of alkali metal cations on the condensation of crown-ether benzaldehydes with 2-methylbenzothiazole

Methods for the synthesis of unknown 2-styrylbenzothiazoles containing crown ether moieties with different combinations of O, S, and N-heteroatoms based on the Wittig reaction or condensation of 2-methylbenzothiazole with crown-ether benzaldehydes in the presence of strong bases or acids are proposed. The condensation in the presence of bases is accompanied by complex formation with participation of the crown ether moiety of the benzaldehyde. The complex formation has a pronounced influence on the yield of the target product and the pattern of condensation of 2-methylbenzothiazole with crown-ether benzaldehydes.     

Reaction of substituted iron phthalocyanines with dioxygen in acidic medium

The reaction of acidic form of the substituted icon phthalocyanine complex (3-PhS- 5-Bu^t)⁴pcFe (pcFe) with dioxygen in o-dichlorobenzene in the presence of dichloroacetic acid (HX) was investigated. The oxidation of HpcFeX gives the corresponding radical cation, which was confirmed by the stoichiometry of reduction of the product formed in this reaction with a two-electron reducing agent. The kinetic equation obtained on the basis of dependences of the oxidation rate on the HpcFeX, HX, and O₂ concentrations are consistent with the reaction mechanism that implies the formation of a HpcFeX complex with O₂ and its transformation to give a radical cation under the action of HX.Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1592–1597, August, 2004.     

Azoles and Azines: CXIX. Alkylation of 5,5'-(4-Nitrobenzylidene)bis(2-thiobarbituric) Acid and 5-(4-Nitrophenyl)-2,8-dithioxo-5,7,8,9-tetrahydro-2H-pyrano[2,3-d:6,5-d']dipyrimidine-4,6(1H,3H)-dione with Haloacetic Acids and Their Esters

5,5'-(4-Nitrobenzylidene)bis(2-thiobarbituric) acid and 5-(4-nitrophenyl)-2,8-dithioxo-5,7,8,9-tetrahydro-2H-pyrano[2,3-d:6,5-d']dipyrimidine-4,6(1H,3H)-dione, similar to unsubstituted 2-thiobarbituric acid, readily react with haloacetic acids and their esters to form regioselectively the S-alkylation products. The alternative routes fo 5,5'-(4-nitrobenzylidene)bis[(4-hydroxy-6-oxo-1,6-dihydropyrimidine-5,2-diyl)sulfanyl]diacetic acids, based on condensation of 4,6-dihydroxypyrimidin-2-ylthioacetic acid with carbonyl compounds followed by cyclodehydration to [(5-(4-nitrophenyl)-4,6-dioxo-3,5,6,7-tetrahydro-4H-pyrano[2,3-d:6,5-d']dipyrimidine-2,8-diyl)di(sulfanyl)]diacetic acid derivatives, are less efficient. Alkylation of 2-thiobarbituric acid with ethyl bromoacetate in ethanol in the presence of alkali yields 5-(2-oxo-2,5-dihydro-1,3-thiazol-4-yl)-2-thiobarbituric acid.     

Carbofunctional silacyclobutanes

A four-step synthesis of 1-(-ydroxyalkyl)- and 1-(4-hydroxyphenyl)silacyclobutanes was carried out. The influence of the structure of the initial compounds and the reaction conditions on the ratio of the reaction products formed was studied. The stability of the silacyclobutane alcohols and the hydrolysis of their trimethylsilyl ethers were investigated.For preliminary communication, see Ref. 6.Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 4, pp. 946–954, April, 1996.     

Macrocycle opening in crown ethers

Macrocycle opening in derivatives of benzocrown ethers under the action of amines is affected by the nature of the heteroatoms in the macrocycle, the nature of the functional group in the benzene ring of the crown ether, and the length, branching, and number of hydrocarbon radicals at the amine nitrogen atom. A distinguishing feature of this reaction is the template effect of MeNH₃ ⁺, Me₂NH₂ ⁺, Na⁺, and K⁺ ions.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 687–692, March, 1996.For Part I see Ref. 1.     

Pre-organization of diarylideneacetonyl crownophanes in single crystals to photochemical transformations

Specific features of crystal packings and pre-organization of diarylideneacetonyl crownophane molecules to solid-phase photochemical transformations were studied on the basis of X-ray diffraction data using methods of simulation of molecular crystal packings. The tendency of the most part of the synthesized macrocyclic E,E-isomers to the formation of homochiral crystals (P2₁2₁2₁) was revealed, while (23E,26E)-11,12,14,15-tetrahydro-8H-dinaphtho-[2,1-k:1′,2′-r][1,4,7,10]tetraoxacyclononadecine-23,26-dien-25(9H)-one is prone to polymorphism. A phenomenon of solid-phase stereospecific photochemical dimerization of molecules according to the syn-head-to-tail type without crystal destruction (single crystal—single crystal transformation) was found for one of the modifications of this crownophane.