S. M. Peregudova

Redox-active ferrocene-modified pyrimidines and adenine as antitumor agents: structure, separation of enantiomers, and inhihibition of the DNA synthesis in tumor cells

The structures, electrochemical properties, enantiomeric separation of ferrocenyl-(alkyl)pyrimidines and ferrocenyl(ethyl)adenine and their effects on the DNA synthesis in tumor cells were studied. Enantiomeric mixtures were separated by HPLC on modified cellulose as the chiral selector. The electrochemical properties of compounds were studied by cyclic voltammetry. All compounds have reversible single-electron redox transition in the region of 0.52–0.60 V, which belongs to ferrocene—ferrocenium with a positive shift compared to ferrocene (0.52 V). The molecular structure of 1-N-(ferrocenylbenzyl)-5-iodocytosine was studied by X-ray diffraction. 1-N-(Ferrocenylethyl)adenine was studied for ability to inhibit the DNA synthesis in the human ovarian cancer cell culture by the 3H-thymidine test.

Electrochemical properties of transition metal complexes with C60 and C70 fullerne ligands (review)

Abstract-The electrochemical properties of exohedral complexes of transition metals with metallofragments coordinated to C60 and C70 fullerene ligands in different coordination modes are surveyed. The effect of the nature, composition, and structure of metal-containing fragments on the electrochemical properties of these complexes and stability of products formed in the oxidation and reduction of complexes is discussed.

Ruthenium carborane complexes: a relationship between the structure, electrochemical properties, and reactivity in catalysis of polymerization processes*

The ruthenacarborane complexes of the exo-nido- and closo-structure, namely, diamagnetic exo-nido-5,6,10-[RuCl(PPh3)2]-5,6,10-(μ-H)3-10-H-7,8-(CH3)2-7,8-C2B9H6, 3,3-[Ph2P(CH2)nPPh2]-3-H-3-Cl-closo-3,1,2-RuC2B9H11 (n = 4, 5), paramagnetic 3,3-[Ph2P(CH2)nPPh2]-3-Cl-closo-3,1,2-RuC2B9H11 (n = 2–5), and their some ortho-phenylenecycloboronated derivatives, were studied by cyclic voltammetry. All chelate closo-complexes are characterized by reversible redox transitions, while the exo-nido-complex is liable to irreversible oxidation. Shortening of the methylene link in the diphosphine ligand of closo-ruthenacarboranes and/or the introduction of ortho-phenylenecycloboronated moieties and methyl substituents to the carbon atoms of the {C2B9} ligand lead to a decrease in the redox potential and electron density redistribution to the metal atom. A comparison of the experimental results on methyl methacrylate polymerization in the presence of the catalytic systems based on the studied metallacarboranes with the data on their electrochemical characteristics suggests that the efficiency of using the ruthenium complexes as catalysts is mainly determined by steric factors.

A palladacyclic azobenzene derivative as a catalyst for carbon-carbon bond formation reactions

A bis-chelated palladacycle in which the Pd atom is [(C, N)(C, N)]-tetracoordinated to two azobenzene ligands proved to be a moderately active catalyst for the Suzuki and Heck reactions. A voltammetric study revealed that the two-electron oxidation of this complex is accounted for by the irreversible PdII/PdIV transition.

A novel type of catalysts for asymmetric oxidative coupling of 2-naphthol

Stereochemically inert, positively charged chiral octahedral complexes of CoIII and CrIII were used as catalysts for asymmetric oxidative coupling of 2-naphthol. The reaction product 1,1´-bi-2-naphthol was produced with a yield of up to 74% and enantiomeric excess of up to 22%. The reduction and oxidation potentials of a series of CoIII and CrIII cationic complexes were measured.

Electrochemical oxidation and reduction of osmium and iridium complexes with fullerene C60

The electrochemical oxidation and reduction of a series of complexes of platinum-group metals (Os, Ir, and Rh) with fullerene C60 with common formula C60[MLn] (MLn is the metal and the metal-bonded ligands) in the tetrahydrofuran solution are studied using the method of cyclic voltammetry. The effect of metal and ligands on the variations in the redox properties of complexes and stability of anions, which are formed in the reduction, is considered. It is shown that all complexes studied are reduced more difficultly than free fullerene, and the reduced forms of metallofullerenes are less stable as compared with free fullerene anions.

SYNTHESIS AND STUDY OF ETA 5-C5H5-3,1,2-MIIIC2B9H11-NFN (M = CO, FE; N = 1-4)

B-Flourosubstituted cyclopentadienyldicarbollylcobalt and -iron were synthesized. Electrochemical studies of iron η5-C5H5-3,1,2-FeC2B9H11−nFn (n = 2–4) complexes were carried out.19F NMR, UV, and IR spectra of the cobalt and iron complexes were obtained.

Investigation of the photoinduced energy transfer in the supramolecular complexes of styryl dyes

Self-assembly of monostyryl dye of benzothiazole series with symmetric and asymmetric bisstyryl dyes based on dibenzo-18-crown-6 ether has been studied by optical and NMR spectroscopies. The photoinduced energy transfer between monoand bisstyryl dyes in supramolecular assembly has been analyzed. The cascade energy transfer in the supramolecular complex of monostyryl dye with asymmetric bisstyryl dye has been suggested.

Electroreduction of cationic fluorene complexes of manganese

Using cyclic voltammetry method, the reduction of cationic η6-fluorene complexes of manganese [(η6-9-R-C13H9)Mn(CO)2L]PF6 (L = CO, R = H (1+); L = CO, R = CH3 (2+); L = PnBu3, R = H (3+); L = CO, R = tBu (4+)) is studied. It is shown that, depending on the nature of a substituent in the position 9 of the fluorene ligand, the reduction occurs either with the detachment of an H atom from position 9 to give zwitterion compounds (complexes 1±, 2±, 3±) or with the attachment of an H atom into the coordinated ring of the fluorene ligand to given η5-cyclohexadienyl complex (η5-9-tBu-C13H9)Mn(CO)3 (5).

Electrocatalytic Reduction of Polyfluoroalkyl Chlorides in the Presence of a Nickel Complex

It is discovered that the salenNi complex exhibits high catalytic activity in respect to polyfluoroalkyl chlorides, which require a high cathodic potential for their reduction. A preparative electrochemical hydrogenolysis of the carbon–chlorine bond in polyfluorohexyl chloride H(CF2)6Cl is performed.