D. P. Krut’ko

New supramolecular synthons based on 3d transition metal complexes with bidentate bispidines: synthesis and structural, spectroscopic, and electrochemical studies

A new supramolecular synthon, a 2L: 1M complex of bidentate bispidine with transition metal, was suggested. A number of complex compounds of 1,5-dimethylbispidin-9-one with Cuii, Niii, and Coii salts (perchlorates, chlorides, bromides, nitrates, trifluoroacetates) were synthesized. The structure and composition of complexes obtained were estimated based on the combination of physicochemical methods of analysis (elemental analysis, X-ray diffraction analysis, NMR, IR, and Raman spectroscopy, electron absorption spectroscopy, ESI mass spectrometry, CVA). The composition of most complexes in the solid state corresponds to the formula ML2X2, and in a number of cases the fragment [ML2]2+ is retained in solution, which was shown by NMR spectroscopy for nickel complexes and by mass spectrometry for copper complexes. In the case of copper chloride, the composition of the acetonitrile solutions in the presence of the ligand depends on the ratio of starting compounds and their concentration: an increase in proportion of CuCl2 and concentration shifts the equilibrium to the side of complexes with higher nuclearity. A 2L: 1M complex of bispidine with metal was for the first time structurally characterized using copper(ii) nitrate derivative as an example. The CVA method showed existence of reversible electrochemical reduction of the metal for a number of complexes (the products of the reaction of 1,5-dimethylbispidin-9-one with nickel(ii) and cobalt(ii) chlorides, as well as with nickel(ii) bromide). According to the IR and Raman spectra, chelation of metals with 1,5-dimethylbispidin-9-one leads to the shift of the absorption band of the ligand carbonyl group from 1700 to 1721–1744 cm−1. Nickel(ii) and copper(ii) perchlorates and nitrates were concluded to be the most promising complexation agents for the binding of two NH,NH-bispidine ligands in a coordination polymer.

On the regioselectivity of alkylation of the (trimethylsilyl)tetramethylcyclopentadienide anion. A new approach to the synthesis of 1,2,3,4-tetramethylfulvene

The regioselectivity of alkylation of lithium (trimethylsilyl)tetramethylcyclopentadienide C5Me4SiMe3−Li+ was studied by 1H and 13C NMR spectroscopy using its reactions with MeI, MeOTs, ClCH2CH2Br, and ClCH2CH2I in different solvents as representative examples. Sterically non-hindered MeI and MeOTs presumably attack the C atom bonded to the silyl group giving 1,2,3,4,5-pentamethylcyclopentadienylsilane. For bulkier alkyl halides, such as ClCH2CH2Br and ClCH2CH2I, the regioselectivity of alkylation changes to form preferentially gem-dialkyl-substituted cyclopentadienes. The reaction of C5Me4SiMe3−Li+ with formaldehyde affords 1,2,3,4-tetramethylfulvene in a high yield, providing an alternative synthetic approach to a number of ω-functionalized peralkylated cyclopentadienes. The quantum-chemical calculations of the C5Me4SiMe3− anion by the RHF and DFT (RMPW1PW91) methods in the valence-split 6-311+G(d,p) basis set are in good agreement with the experimental data.

New stereoselective intramolecular redox reaction in the system of 3,7-diazabicyclo[3.3.1]nonan-9-one

The ring opening in the 1-benzyl-5,7-dimethyl-6-oxo-1-azonia-3-azaadamantane chloride under the treatment with excess aqueous alkali led to a stereoselective formation of anti-1,5-dimethyl-7-benzyl-3-formyl-3,7-diazabicyclo[3.3.1]nonan-9-ol whose structure was established by means of X-ray diffraction analysis and NMR spectroscopy. A reaction mechanism was suggested involving an intramolecular redox hydride transfer.

Synthesis, structure, electrochemistry, and photophysics of 2,5-dibenzylidenecyclopentanones containing in benzene rings substituents different in polarity

A series of cross-conjugated dienones was synthesized to study the dependence of physicochemical characteristics on the nature of substituents in the aromatic groups of symmetric cyclopentanone dibenzylidene derivatives. The structure of compounds was established by electronic, IR, and NMR spectroscopy and X-ray diffraction study. All the compounds obtained possess the E,E-geometry. In the crystalline state, the arrangement of the dienone molecules is unfavorable for the intermolecular [2+2] photocycloaddition to take place. The low-temperature phases transition for unsubstituted diphenyl derivative of cyclopentanone was detected using variable-temperature X-ray diffraction and differential scanning calorimetry. Oxidation and reduction potentials of the dienones were measured by cyclic voltammetry. Their dependence on the nature and placement of substituents in the benzene rings was demonstrated. A linear correlation (R = 0.9343) between the difference of electrochemical oxidation and reduction potentials and the energy of the long-wavelength absorption maximum was found, that allows us to recommend the use of the data obtained in the correlation analysis of other compounds of this class.

A study of the morphology of acrylonitrile-methylacrylateitaconic acid/itaconic acid derivative copolymers synthesized in a supercritical carbon dioxide medium

Ternary copolymers of acrylonitrile with methylacrylate, itaconic acid (IA), and its derivatives, namely, monomethyl ester (MME), monoethyl ester (MEE), monoamide, and mono-n-octylamide, were synthesized in a supercritical carbon dioxide medium. The morphology of the synthesized copolymers was studied by scanning electron microscopy. Copolymers with IA, MME, and MEE were obtained in the form of regularly shaped particles of nearly 1 μm in size without the addition of stabilizers.

1,7-Dimethyl-1,7-dichloromethyl-5,8-ethenodecalin-3-ene-2,6-dione. Structure, bromination, electrochemistry

The structures of 1,7-dimethyl-1,7-bis(dichloromethyl)-5,8-ethenodecalin-3-ene-2,6-dione, the dimer of 6-methyl-6-dichloromethyl-cyclohexa-2,4-dien-1-one, and of products of its bromination were established by XRD analysis. The dependence of composition of the products of bromination on the ratio of reactants was established. Electrochemical reduction of the dione and its bromine-containing derivatives was studied.

Bromination of 6-Dibromomethyl-6-methylcyclohexyl-2,4-dien-1-one

Bromination of 6-dibromomethyl-6-methylcyclohexyl-2,4-dien-1-one (I) with molecular bromine was studied at different ratios of reactants and varied reaction time. A number of tri-, tetra-, penta-, and hexabromo derivatives was obtained, which were characterized by 1H, 13C, IR, UV spectroscopy and elemental analysis. The molecular structure of (2R,3R,4S,5S,6R)-2-dibromomethyl-2-methyl-3,4,5,6-tetrabromocyclohexan-1-one (V) was revealed using XRD. It was shown that 2-bromo-6-dibromomethyl-6-methylcyclohexyl-2,4-dien-1-one (III) upon standing for six months at room temperature dimerized quantitatively via Diels-Alder reaction to form IX. Dimer IX was investigated by the methods of cyclic voltammetry (CVA) and rotating disk electrode (RDE) in a solution of DMF on glassy carbon electrode.

Carboxylation of aromatic compounds in a supercritical carbon dioxide medium

The reaction of direct carboxylation of benzene and its derivatives PhX (X = Me, Br, Ph, OPh, OMe), as well as mesitylene, durene, and ferrocene, in a supercritical CO2 medium in the presence of various Lewis acids (AlCl3, FeCl3, ZrCl4, and ZnCl2) is studied. It is shown that, in all cases, secondary reactions proceed faster than the primary reaction of carboxylic acid formation. For the thoroughly studied AlCl3-CO2toluene system, optimal conditions of the formation of n-toluic acid are determined. For the AlCl3-CO2-benzene system, as an example, quantum-chemical calculations of the characteristics of the allowed pathways of the carboxylation reaction are performed.

Crosslinked α-olefin-diene copolymers prepared using a metallocene catalyst deposited on the surface of SiO2-modified Fe3O4: Ferromagnetic oil sponges

The structure of zirconocene is determined experimentally. Zirconocene is found to catalyze effectively the copolymerization of α-olefins with nonconjugated dienes in the presence of minimal amounts of methylalumoxane as an organoaluminum activator. On the basis of a highly ferromagnetic carrier (a product of the reaction between Fe3O4 microparticles and Si(OEt)4), a deposited zirconocene catalyst is obtained. Using the latter, copolymers of α-olefins (1-hexene, 1-octene, and 1-decene) with 1,7-octadiene and 1,4- di(3-butenyl)benzene are synthesized. The obtained ferromagnetic copolymers demonstrate properties of effective absorbents of hydrocarbons, namely, oil sponges. A copolymer of 1-octene and 1,4-di(3-butenyl) benzene is found to possess the maximum adsorption capacity (up to 8) in the studied series.

Electrochemical reduction of 4-methyl-4-(trichloromethyl)cyclohexa-2,5-dien-1-one

The properties of 4-methyl-4-(trichloromethyl)cyclohexa-2,5-dien-1-one which contains the trichloromethyl substituent at a quaternary carbon atom have been studied by cyclic voltammetry, rotating disk electrode voltammetry, and preparative electrolysis. Reductive dehalogenation involves initial two-electron reductive elimination of one of the geminal chlorine atoms followed by consecutive addition of proton, simultaneous elimination of the two residual halogen atoms to form carbene, and rearrangement of cyclohexadienone into the corresponding 4-methylcyclohepta-2,4,6-trien-1-one.