G. V. Shilov

Synthesis and Structure of 2-Ethoxy- and 2-Aminomethylidene- 3-fluoroalkyl-3-oxopropionates

Condensation of ethyl 3-polyfluoroalkyl-3-oxopropionates with excess triethyl orthoformate gave ethyl 3-polyfluoroalkyl-2-ethoxymethylidene-3-oxopropionates which reacted with primary aliphatic, aromatic, and heterocyclic amines to form ethyl 2-alkyl(aryl, hetaryl)aminomethylidene-3-polyfluoroalkyl-3-oxopropionates. According to the X-ray diffraction and IR data, the latter exist in the crystalline state as the corresponding E isomers, while in solution (NMR data), as mixtures of Z and E isomers. Condensation of ethyl 2-ethoxymethylidene-3-oxopropionates with secondary heterocyclic amines (morpholine and pyrrolidine) led to the formation of 2-morpholino(pyrrolidin-1-yl)methylidene-3-fluoroalkyl-3-oxopropionates which were shown to exist as Z isomers both in the crystalline state and in solution.

[Fe2(μ-SC5H4N)2(NO)4] as a New Potential NO Donor: Synthesis, Structure, and Properties

A new potential donor of nitrogen monoxide, a binuclear iron sulfur nitroso complex, was prepared by exchange reaction of Na2Fe2(S2O3)2(NO)4 with pyridine-2-thiol in the presence of sodium thiosulfate at pH 12. The molecular and crystal structures of [Fe2(μ-SC5H4N)2(NO)4] were studied by X-ray diffraction analysis. The type of iron coordination by pyridine-2-thiol in the presence of a coordinated NO molecule was determined. In vacuum, the structure of the complex is destroyed, which is accompanied by NO evolution, while exposure to UV radiation results in decomposition of the complex and in a release of N2O.

A new series of ET-based organic metals: Synthesis, crystal structure and properties

Abstract New two-dimensional organic metals ET 2 [Hg(SCN) 3−n X n ], X=F, Cl, Br, I have been synthesized and investigated. ET 2 [Hg(SCN)Cl 2 ] and ET 2 [Hg(SCN) 2 X] (X=Cl, Br or (0,33 Cl+0, 66 Br) have been found isostructural. Cationic sheets of x -type alternate with anionic sheets. The [Hg(SCN) 3−n X n ] − (n=1,2) anions have a polymeric-structure and form chains with one or two SCN bridge ligands. The conductivity of salts with X=F is of a metallic character down to helium temperature, while all salts with X=Cl(n=1,2), (Cl 0,33 Br 0,66 ), Br exhibit metallic behaviour of their conductivity till 35, 50, 70 and 140 K, respectively, then they become insulators The salt with X=I is semiconductor.

Synthesis, structure, NO donor activity of iron–sulfur nitrosyl complex with 2-aminophenol-2-yl and its antiproliferative activity against human cancer cells

A new tetranitrosyl binuclear iron complex, [Fe2(SC6H6N)2(NO)4] (1), has been synthesized by two methods. Molecular and crystalline structure of 1 were determined by X-ray analysis; the complex is binuclear of “μ-S” type with ~2.7052(4) Å between the irons. The compound crystallizes in monoclinic, space group P21/n, Z = 2; parameters of the unit cell: a = 6.6257(2) Å, b = 7.9337(2) Å, c = 16.7858(4) Å, β = 96.742(2)°, V = 876.26(4) Å3. Parameters of Mössbauer spectrum for 1 are: isomer shift δFe = 0.096(1) mm/s, quadrupole splitting ΔEQ = 1.122(1) mm/s, line width 0.264(1) mm/s at 293 K. As follows from the electrochemical analysis of aqueous solutions of 1, it generates NO in protonic media without additional activation. NO amount and the rate of its activation are much higher in acidic solutions than in neutral and alkali ones. The constants of hydrolytic decomposition of 1 were calculated. The geometry and electronic structure of isolated 1 were studied using the density functional theory. Differential sensitivity of four lines of human tumor cells of various genesis to 1 has been determined (ovarian carcinoma (SCOV3), large intestine cancer (LS174T), mammary gland carcinoma (MCF7), and non-small cell carcinoma of lung (A549)); dependence of tumor cells amount on the complex concentration has been studied in order to use the complex as a promising antitumor agent for trials in vivo.

2-Hydroxy-4-methylbenzenesulfonic acid dihydrate: Crystal structure, vibrational spectra, proton conductivity, and thermal stability

The crystal and molecular structure of 2-hydroxy4-methylbenzenesulfonic acid dihydrate C6H3(CH3)(OHSO−3 H5O2+ (I) was studied by X-ray diffraction and vibrational spectroscopy. The compound crystallized in the monoclinic crystal system; crystal data: a=10.853(2) Å, b=7.937(2) Å, c=12.732(3) Å, β=112.13(3)°, V=1015.9(4)Å3,Z=4,dcalc=1.466g/cm3,spacegroupP21/c,Rf=0.0486,GOOF=1.161.The S-O distances in the sulfonate group differed substantially (S1-O2 1.439(2) Å, S1-O3 1.455(2) Å, and S1-O4 1.464(2) Å. The symmetry of the H5O2 cation decreased due to proton displacement toward one of the two water molecules. XRD data on the asymmetry of H5O2 were confirmed by IR and Raman spectral data. The strong triplet at 2900, 3166, 3377 cm−1 in the IR spectrum of I corresponds to different types of H-bond and shifted to 2185, 2363, 2553 cm−1 after deuteration. The proton conductivity of the compound was measured by impedance spectroscopy: 6 × 10−7 S/cm at 298 K (32 rel %), Eact=0.4±0.01 eV. The conductivity increased to 10-3 S/cm, Eact=0.1 eV when ambient humidity increased to 60 rel %.

Influence of aromatic ligand on the redox activity of neutral binuclear tetranitrosyl iron complexes [Fe2(μ-SR)2(NO)4]: experiments and quantum-chemical modeling

Reduction of neutral binuclear nitrosyl iron complexes of “μ-S” structural type [Fe2(SR)2(NO)4] with R = 3-nitro-phenol-2-yl, 4-nitro-phenol-2-yl, 5-nitropyridine-2-yl and pyridine-2-yl in aprotic solution has been studied by a cyclic voltammetry (CVA) method at a wide range of potential scan rates. A complex with R = 3-nitro-phenol-2-yl was synthesized for the first time; therefore it was studied by X-ray and Mossbauer spectroscopy. The parameters of the Mossbauer spectrum are: isomer shift δFe = 0.115(1) mm s−1, quadrupole splitting ΔEQ = 1.171(1) mm s−1, and line width = 0.241(1) mm s−1 at 85 K. From the current–voltage curve, the transfer of the first electron was found to be reversible, and the redox-potentials of these reactions were determined. The further reduction of the complexes was determined to be irreversible because the product of the second electron addition is instable and decomposes partially during the potential scan. Calculations of geometric and electronic structures of monoanions and dianions of the complexes under study and their theoretical redox-potentials were performed by DFT methods. Introduction of the electron-acceptor NO2 group into the phenyl and pyridine rings of sulfur-containing ligands of the nitrosyl iron complexes was found to affect the geometry of the anions and the distribution of the additional negative charge, as well as to increase the redox-potential and to facilitate reduction of these complexes.

Structures of bis(1-methyltetrazole-5-thiolato)(tetranitrosyl)diiron and its intermediates in solutions

Single crystals of an iron complex with 1-methyltetrazole-5-thiol of the formula [Fe2(SC2H3N4)2(NO)4] (I) were obtained and examined by X-ray diffraction. According to electrochemical data, tetranitrosyl binuclear complex I rapidly decomposes in protic solvents with elimination of NO. The maximum amount of NO generated by complex I in 1% aqueous DMSO is ∼900 nmol. This amount is reduced by half 15 min after the beginning of the decomposition under anaerobic conditions. The dinitrosyl mononuclear intermediates [Fe(SC2H3N4)2(NO)]− and [Fe(SC2H3N4)2(NO)2]− were detected in solutions and identified by EPR spectroscopy and mass spectrometry. The low number of spins per complex in solutions indicates that the mononuclear complexes undergo further decomposition into NO and the species [Fe(SC2H3N4)3]−, [SC2H3N4]−, and [Fe4S3(NO)7]−. Complex I was found to be substantially more stable in DMSO than in methanol and 1% aqueous DMSO.

New BETS based molecular conductors with bromomercurate anions

Five BETS-based salts with different bromomercurate anions have been isolated. Some of these compounds ungergo the M-I transition with the temperature decrease, the others behave as metals. Among them a salt of nonstoichiometric composition BETS 4 Hg 2.84 Br 8 has been found with κ-type packing of organic layers.

[Bu4N]2[Fe2(μ-S2O3)2(NO)4]: Synthesis, Structure, Redox Properties, and EPR Study

The [n-Bu4N]2[Fe2(μ-S2O3)2(NO)4] complex was studied using X-ray diffraction analysis, cyclic voltammetry, and EPR spectroscopy, and its crystal structure was determined. The redox properties of the [Fe2(μ-S2O3)2(NO)4]2–anion in CH3CN and CH2Cl2solutions were studied. An addition of excess reducer (sodium thiosulfate) to the thiosulfate complex was shown to produce an EPR signal with g= 2.03 typical of the mononuclear iron dinitrosyl complexes. The mechanism for [Fe2(μ-S2O3)2(NO)4]2–reduction was suggested.

The Structure and Properties of Phenol-2,4-disulfonic Acid Dihydrate

The crystal and molecular structure of phenol-2,4-disulfonic acid dihydrate was determined by X-ray structure analysis. All hydrogen positions in the crystal structure were found using difference Fourier syntheses. Oxonium cations and acid anions were linked in the crystal structure by short H-bonds, and the phenol OH group participated in two weak H-bonds with sulfo group oxygens simultaneously. The IR frequency corresponding to νs, as (H3O+) vibrations decreased to 2700 cm−1 under the influence of short H-bonds between oxonium cations and anions. The contour of the corresponding absorption band became anomalously broad. A discrete maximum was observed at 3412 cm−1 on the high-frequency wing of this band; this maximum was assigned to OH stretching vibrations of the phenol group. The protonic conductivity of the compound measured by impedance spectroscopy was 2.5 × 10−6 Ω−1 cm−1 at 298 K in a vacuum, Ea = 0.37 ± 0.01 eV. An increase in the humidity of the environment to 15% at room temperature increased conductivity from 10−6 to 10−5 Ω−1 cm−1, Ea = 0.27 ± 0.02 eV.