Showing papers by "Andrei V. Churakov published in 2005"
TL;DR: In this paper, the structures of a series of metallatranes, N(CH2CH2O)3M-X (I-IV), where M=Si, Ge, Sn and Pb, and X=H, F, Cl, Br, HO, CH3, (CH3)2N, ( CH3)3N+ were studied using DFT calculations with full geometry optimization.
Abstract: The structures of a series of metallatranes, N(CH2CH2O)3M–X (I–IV), where M=Si, Ge, Sn and Pb, and X=H, F, Cl, Br, HO, CH3, (CH3)2N, (CH3)3N+ were studied using DFT calculations with full geometry optimization. The obtained results are in good agreement with gas electron diffraction data. The transannular bond M←N length depends on the nature of M and axial X substituent and the strength of M←N bond increases in Si
46 citations
TL;DR: A series of new viologen analogues bearing two ammonioalkyl groups (2−4) were synthesized in order to study their complexation with bis(18-crown-6)stilbene (1b) as mentioned in this paper.
Abstract: A series of new viologen analogues bearing two ammonioalkyl groups (2–4) were synthesized in order to study their complexation with bis(18-crown-6)stilbene (1b). Electronic spectroscopy and 1H NMR measurements show that in acetonitrile, bis(crown) stilbene 1b forms highly stable 1 : 1 and 2 : 1 charge-transfer (CT) complexes with π-acceptors 2–4 owing to host–guest bonding. The influence of geometric and electronic factors on the complex formation constants are discussed. The structures of the supramolecular CT complexes are analyzed on the basis of 1H and 13C NMR data obtained in solution and in the solid state. X-Ray diffraction data for 1b and for model tetramethoxystilbene are also reported.
38 citations
TL;DR: In this paper, eight perhydrates Ph4X+Hal−·nH2O2 (X = P, As; Hal = Cl, Br; n = 0.98-1.90) were prepared and their structures were determined by X-ray crystallography.
Abstract: Eight novel perhydrates Ph4X+Hal−·nH2O2 (X = P, As; Hal = Cl, Br; n = 0.98–1.90) were prepared and their structures were determined by X-ray crystallography. All the structures are formed by parallel infinite zigzag chains of Ph4X+ cations and hydrogen-bonded anionic chains [(H2O2)x(Hal−)y]∞ (x, y = 1, 2). Hydrogen peroxide is partially substituted by admixed water molecules. Some of the studied perhydrates were found to be isostructural with the related hydrates Ph4X+Hal−·nH2O.
28 citations
TL;DR: In this article, a series of 2-R2P-substituted indenes were obtained via Pd-catalyzed reactions of 2bromo-1H-indene (or 1Hinden-2-yl trifluoromethane sulfonate) with R2PH/Et3N.
23 citations
TL;DR: Both cis- and trans-isomers were studied, and cis-configuration was found to be more thermodynamically stable for all three compounds and the transition states for possible cis <--> trans rearrangement processes in 1-3 were calculated.
Abstract: Synthesis of the title compounds, viz. [RN(CH2CHR‘O)2]2Ge (1, R = Me, R‘ = H; 2, R = Me, R‘ = Ph; 3, R = Ph, R‘ = H), by the reaction of 2 equiv of corresponding dialkanolamines RN(CH2CHR‘OH)2 (4, ...
22 citations
TL;DR: In this paper, the authors showed that 4-styrylpyridine with a 15-crown-5 ether fragment can bind metal cations through the participation of two centers: the crown ether moiety and the heterocyclic part.
18 citations
TL;DR: In this paper, a mixture of rac-and meso-Me2Si(2-Me-4,6-R2C9H3-η5)2MCl2, where R = Me, i-Pr and M = Zr, Hf, were obtained by a treatment of MCl4 by dilithium salts of the respective bis(2,4, 6-trialkylindenyl)dimethylsilanes in toluene.
11 citations
TL;DR: The crystal and molecular structures of six perchlorates (viologen analogues) are studied in this article, which serve as models of the acceptor component of new charge transfer complexes containing bis(18-crown-6)stilbene as the donor.
Abstract: The crystal and molecular structures of six perchlorates (viologen analogues) are studied. These compounds serve as models of the acceptor component of new charge-transfer complexes containing bis(18-crown-6)stilbene as the donor. The polycyclic aromatic system of divalent cations is demonstrated to be virtually planar. In all cations, the side chains at the nitrogen atoms are oriented in opposite directions almost perpendicular to the plane of the cyclic system. This orientation of the spacers of these carbocations is indicative of their preorganization for the formation of 1: 2 charge-transfer complexes. Analysis of the crystal packings provides evidence that two positive charges on the conjugated systems of the organic cations and the perchlorate anions play a destructive role in the formation of stacking motifs. An increase in the size of the conjugated system and the involvement of an aromatic solvent molecule as an additional building block in a supramolecular system are favorable for the formation of a stacking supramolecular architecture.
10 citations
TL;DR: In this article, the molecular structures of zirconocene dichloride compounds were established by X-ray diffraction analyses, with the Zr-CH2 bond retained.
9 citations
TL;DR: In this paper, the structure of treo-N(CH2CH2O)2(CHPhCHPhO)GeC CPh (1), erythro-n(CH 2 CH2CH 2O) 2(CHPHCHPhPhO),GeCCPh (2), N(CHCH2CPh2O), n(CHCPh 2O), and cPh CPh 2 (3) were determined by X-ray diffraction studies.
7 citations
TL;DR: In this article, two new monocyclopentadienyl zirconium complexes, [C5H4C(Me) = CH2]ZrCl3 · 2THF and[C5Me4CH=CH2] ZrCl 3 · 2thF, were synthesized by X-ray diffraction.
Abstract: Regioselectivity of the reactions of lithium vinyl- and isopropenylcyclopentadienides C5H4C(R)=CH2
-Li+(R = H, Me) and lithium tetramethylvinylcyclopentadienide C5Me4CH=CH2
-Li+ with various electrophilic agents (Me3SiCl, Me3SnCl, Et2PCl, 2-chloro-1, 3-dioxaphospholane, and MeI) was studied. Two new monocyclopentadienyl zirconium complexes, [C5H4C(Me) = CH2]ZrCl3 · 2THF and [C5Me4CH=CH2]ZrCl3 · 2THF, were synthesized. Their crystal structures were established by X-ray diffraction. The results of quantum chemical calculations for the C5H4C(R) = CH2
- (R = H, Me) and C5Me4CH=CH2
- anions by the DFT method (RMPW1PW91) with the 6-311+G(d, p) split valence basis set are in good agreement with experimental data on the regioselectivity of their reactions with electrophilic agents.
TL;DR: In this article, the synthesis of polypropylene (PP) in bulk was studied in the presence of polymethylalumoxane-activated metallocenes 9 and 10 in the temperature range of 30 −70°C.
Abstract: Isomeric 1-(fluoren-9-yl)-2-(2-methyl-5, 6-dihydrocyclopenta [f]-1 H-indenyl) ethanes 1a,b and C1-symmetric metallocenes, viz., rac-1-(η5-fluoren-9-yl)-2-(2-methyl-5, 6-dihydrocyclopenta [f]-η5-inden-1-yl) ethanezirconium dichloride (9) and rac-1-(η5-fluoren-9-yl)- 2-(2-methyl-5, 6-dihydrocyclopenta [f]η5-inden-1-yl)ethanehafnium dichloride (10), with these ligands were synthesized by modified procedures. The structures of compounds 1b (two crystalline modifications) and 10 were established by X-ray diffraction analysis. The synthesis of polypropylene (PP) in bulk was studied in the presence of polymethylalumoxane-activated metallocenes 9 and 10 in the temperature range of 30–70°C. It was demonstrated that triisobutylaluminum can be used as a cocatalyst. In this case, the molecular weight of PP increases by a factor of ∼2. An increase in the reaction temperature leads to an increase in stereoregularity and crystallinity of PP. The polymer synthesized at high temperatures crystallizes in the γ form. The resulting PP is characterized by a wide range of properties from rigid crystalline thermoplastic to amorphous elastomeric. Samples, which have a high molecular weight and moderate isotacticity, exhibit high elastomeric and durability properties.
TL;DR: Titanatrane CpTi(OCH(CH3)CH2)3N (3) was prepared by the reaction of Cp TiCl3 with N(CH2CH(Ch3)OH)3 in the presence of triethylamine as discussed by the authors.
Abstract: Titanatrane CpTi(OCH(CH3)CH2)3N (3) was prepared by the reaction of CpTiCl3 with N(CH2CH(CH3)OH)3 in the presence of triethylamine. The reaction of CpTi(OMe)3 (8) with N(CH2CH2OH)2(CH2CHPhOH), erythro-N(CH2CH2OH)2(CHPhCHPhOH), and N(CH2CH2OH)2(CH2CPh2OH) gave cyclopentadienyltitanatranes 12–14. Compound 8 reacts with threo-N(CH2CH2OH)2(CHPhCHPhOH) to give a mixture of threo-CpTi(OCH2CH2)2(OCHPhCHPh)N and threo-MeOTi(OCH2CH2)2(OCHPhCHPh)N. Slow hydrolysis of the latter product gave threo-[Ti3O(OMe){(OCH2CH2)2− (OCHPhCHPh)N} 3]2, which was studied by X-ray diffraction analysis. The crystal structures of 3 and 12 were also determined by X-ray diffraction analysis. The titanium coordination polyhedron in these complexes is a distorted trigonal bipyramid in which the equatorial positions are occupied by three oxygen atoms and the axial positions contain the N atom and the Cp group. The titanium—nitrogen distances (2.313(2), 2.291(2) A in two independent molecules of 3 and 2.271(2) A in compound 12) confirm the presence of Ti←N transannular interaction.
TL;DR: The title compound (PhC≡C)4Ge or [Ge(C8H5)4) as mentioned in this paper crystallizes in the space group I\overline 4 with \overline four molecular symmetry.
Abstract: The title compound, (PhC≡C)4Ge or [Ge(C8H5)4], crystallizes in the space group I\overline 4 with \overline 4 molecular symmetry. The coordination polyhedron of the central atom is a slightly distorted tetrahedron, with C—Ge—C angles in the range 107.95 (17)–110.24 (9)°.
TL;DR: In this paper, the reaction of benzylaminate CN-palladacycle with chlorine dioxide was found to produce the 3-chlorine-substituted analog through the formal insertion of chlorine into the Pd-C bond followed by repeated ortho palladation of the modified ligand.
Abstract: The reaction of benzylaminate CN-palladacycle with chlorine dioxide was found to produce the 3-chlorine-substituted analog through the formal insertion of chlorine into the Pd-C bond followed by repeated ortho-palladation of the modified ligand. The structure of the resulting dimeric complex was confirmed by X-ray diffraction study of its triphenylphosphine derivative. A comparison of the 1H NMR spectra of the phosphine adducts of the starting and chlorinated complexes shows high conformational stability of the new palladacycle. Advantages of the new route to conformational stabilization of labile palladacycles are discussed.
Journal Article•
TL;DR: The first X-ray crystallization of the germanium (IV) zinc (II) hydroxyethylidenediphosphonate Zn4[Ge6(OH) 4 (O) 2 (L) 6 ] was performed by as mentioned in this paper.
Abstract: The heterometallic germanium(IV) zinc(II) hydroxyethylidenediphosphonate Zn4[Ge6(OH) 4 (O) 2 (L) 6 ] . ∼38H 2 O (I) (L 4 - is the anion of hydroxyethylidenediphosphonic acid) was synthesized for the first time by two methods and studied by X-ray crystallography. The structural units of the crystal of I are hexanuclear cyclic anions [Ge 6 (μ-OH) 4 (μ-O) 2 (μ-L) 6 ] 8 - , complex zinc cations with different ligand environments, and water molecules of crystallization. These units are joined by an extended hydrogen bond network.
TL;DR: The reaction of the carbidocarbonyl cluster [Fe6C(CO)16]2− with ruthenium(IV) hydroxochloride Ru(OH)Cl3 was studied in this article.
Abstract: The reaction of the carbidocarbonyl cluster [Fe6C(CO)16]2− with ruthenium(IV) hydroxochloride Ru(OH)Cl3 was studied. At 90–100 °C, the reaction gave products of replacement of Fe atoms by Ru in the [Fe6C(CO)16]2− cluster along with degradation products. Treatment of the replacement products with FeCl3 afforded the [Fe2.96Ru3.04C(CO)17] compound (1), which was characterized by X-ray diffraction analysis. The crystals of cluster 1 are composed of two types of octahedral molecules (1a and 1b) in a ratio of 2 : 1. Molecules 1a are in general positions, and molecules 1b are located on twofold axes. In both molecules, the Fe and Ru atoms are disordered over four of six positions.
TL;DR: The reaction of enantiomerically pure 2-hydroxypinan-3-one with ethylenediamine was studied in this article, which can afford either mono- or bis-Schiff"s bases.
Abstract: The reaction of enantiomerically pure (–)-2-hydroxypinan-3-one with ethylenediamine was studied. Depending on the reagent ratio, the reaction can afford either mono- or bis-Schiff"s bases. The enantiomerically pure unsymmetrical terpenoid salen-type ligand was prepared by the reaction of 3-[(2-aminoethyl)imino]pinan-2-ol with salicylaldehyde.
TL;DR: In this article, the mesophase of the p-Ethoxyphenyl p′-pentylbenzoate (I) was studied by X-ray diffraction analysis at 120.0 and 296.0 K.
Abstract: p-Ethoxyphenyl p′-pentylbenzoate (I), which exhibits a mesophase (K 62.6 N 63.3 I), was studied by X-ray diffraction analysis at 120.0 and 296.0 K. In the molecule I, one of the benzene rings is almost coplanar with the carboxy group COO, whereas another benzene ring is twisted with respect to the carboxy group by 65.9°. The geometric parameters of the molecule I are indicative of possible conjugation between the carboxy group and the former benzene ring and the absence of conjugation between this group and the second benzene ring. In the crystal packing, extended molecules I are oriented along the bc diagonal. The mutual orientation of the nearest benzene rings of any two adjacent molecules is T-shaped, which corresponds to a weak C-H...π-type interaction.