Electron-impact studies of organometallic molecules—XI:. Some polyfluoroaromatic derivatives of ferrocene

The mass spectra of eight ferrocene derivatives containing C₆F₅, C₆F₅CO, C₆F₅CH₂ or p-CH₃OC₆F₄ groups attached to one or both cyclopentadienyl rings are described and discussed. In addition to features normally found in the mass spectra of ferrocene compounds, the migration of fluorine to the iron atom leads to the formation of ions such as [C₅H₄COFeF]⁺. The elimination of neutral FeF₂ or C₅H₅FeF molecules is also found.     

Synthesis and properties of furan derivatives. 5. Synthesis of 2-substituted benzoxazoles containing furan fragments

The condensation of imidates and imidate hydrochlorides of furan acids with o-aminophenols gives furyl derivatives of 2-substituted benzoxazoles. Such compounds are also formed in the reaction of furan acids with o-aminophenol in the presence of boric acid.Communication 4, see [1].I. M. Gubkin State Petroleum and Gas Academy, 117917 Moscow. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 896–901, July, 1996. Original article submitted April 16, 1996.     

Synthesis and properties of furan derivatives. 4. Synthesis of 2,5-disubstituted 1,3,4-oxadiazoles containing furan fragments

The condensation of hydrochloride sats of iminoesters of furan acids with hydrazides of carboxylic acids gives 2,5-disubstituted 1,3,4-oxadiazoles containing furan fragments. Such compounds are also formed in the condensation of hydrazides of 5-R-furan-2-carboxylic acids with hydrocloride salts of carboxylic acid iminoesters. The reaction of furan acids with hydrazine dihydrochloride in polyphosphoric acid gave symmetrically disubstituted 1,3,4-oxadiazoles containing furan fragments.Communication 3, see ref. [1].I. M. Gubkin State Petroleum and Natural Gas Institute, 117917, Moscow. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 238–249, February, 1995. Original article submitted January 24, 1995.     

Fe-NMR spectroscopy revisited: ferrocene derivatives containing heterosubstituents

⁵⁷Fe-NMR spectra (16.1 MHz; natural abundance) of mono- and 1,1′-disubstituted ferrocene derivatives (1–15), including two ferrocenophanes (14, 15), could be measured in a much shorter time than expected according to previous reports (500 MHz spectrometer, standard equipment; solutions in 5-mm tubes). Substituents were ^tBu, alkynyl, silyl, germyl, stannyl and boryl groups, and the bridges in the ferrocenophanes were SiMe₂ (14) and Me₂SiSiMe₂ units (15). The δ⁵⁷Fe values cover a fairly large range of >450 ppm. There is a large difference (365 ppm) in ⁵⁷Fe nuclear shielding for the two ferrocenophanes, with the higher ⁵⁷Fe shielding in the [1]ferrocenophane 14. Parallel trends were observed between δ⁵⁷Fe of ferrocene derivatives and δ⁵⁵Mn of comparable sandwich complexes derived from [(η⁵-C₅H₅)Mn(η⁶-C₆H₆)].     

Ferrocene compounds: XVI. Mass-analyzed ion kinetic energy (MIKE) spectra of some monosubstituted ferrocene derivatives

The mass-analyzed ion kinetic energy (MIKE) spectra of some monosubstituted ferrocenes having an unsaturated moiety in the α- or β-position to the cyclopentadienyl ring and β-phenyl-γ-ferrocenoylbutyric acid are presented and discussed.     

Electrochemical studies and potential anticancer activity in ferrocene derivatives

Several ferrocene derivatives (five mononuclear and two binuclear), including the new N-(p-chlorophenyl)-carboxamidoferrocene (1), were synthesized and their anticancer activity investigated. Two of them, 3 and 7, bearing a benzimidazole backbone were the most active against HeLa cells achieving IC₅₀ values of ~5 μM along with 4 with a dipyridylamine ligand (~6 μM). Complex 6, also with a benzimidazole backbone, displayed slightly higher values (~11 μM). Cyclic voltammetry studies show that while the non-cytotoxic ferrocene derivatives 1, 2, and 5 follow a ferrocene-based redox behavior, derivatives 3, 4, 6, and 7 exhibit a more complex mechanism. These complex mechanisms are consistent with a more effective cytotoxic activity. Mössbauer spectroscopy parameters reflect a very small influence of the substituents.     

QSAR and 3D-QSAR studies of the diacyl-hydrazine derivatives containing furan rings based on the density functional theory

QSAR studies of 27 diacyl-hydrazine derivatives containing furan rings were conducted and compared with the DFT method and AM1-MOPAC method. q ² values of 0.61 and 0.40 validated the predictability and reliability of eq. (5) from the DFT method were higher than those of eq. (6) from the AM1-MOPAC method. The DFT-optimized conformations and ESP-fitting charges of the target compounds were also used for 3D-QSAR analysis, including CoMFA and CoMSIA. The leave-one-out cross-validation correlation coefficient and the good correlation between the predicted and experimental activities of excluded test compounds revealed that CoMFA and CoMSIA models were robust. The QSAR results were consistent with the 3D-QSAR results, indicating that the electrostatic and hydrophobic properties of the target compounds were significant to the biological activity. These models are useful tools for predicting the larvicidal activities of new compounds and designing new specific insect growth regulators.     

The liquid crystalline behaviour of ferrocene derivatives containing azo and imine linking groups

The synthesis and mesogenic properties of some Schiff bases containing ferrocene, azobenzene units and flexible end chains with 17 or 18 carbon atoms are reported. The compounds have been characterized by ¹H-NMR and ¹³C-NMR spectroscopy, DSC and optical microscopy in polarized light.     

Electron paramagnetic resonance studies on oxidative polymerization mechanism of furan derivatives

The oxidative polymerization of furan, 3-methylfuran and 2,2′,5′,2″-terfuran, induced by iodine in organic solvents having different donicity, was investigated by time-resolved electron paramagnetic resonance (EPR) spectroscopy. The reaction was monitored starting from the onset of the process and radical species arising from the monomers in early stages of the polymerization reaction were detected. The comparison between experimental and theoretical hyperfine coupling constants, obtained by simulated EPR spectra and theoretical ab initio calculations, respectively, allowed one to structurally characterize the above radical species, thus enabling mechanistic conclusions about oxidative coupling. Moreover, the analysis of the time evolution of EPR spectrum during the oxidative polymerization process was used for evaluating the relative amount of localized and mobile radical species along the polymer backbone, thus getting preliminary information about conjugation extent and electroconducting properties of the final material. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1901–1910, 1998     

Synthesis and physicochemical studies of metal complexes of ferrocene Schiff base derivatives

Two new Schiff bases were prepared by condensing acetylferrocene and 1,1′-diacetylferrocene with S-methyl- dithiocarbazate. Complexes of the two ligands acetylferrocene-1-hydrazono-S-methyldithiocarbazate HmaL and diacetylferrocene-1,1′-dihydrazono-S-methyldithio-carbazate H2daL, with copper(II), nickel(II) and cobalt(II) ions were isolated. The ligands coordinate to the metal ions through either their thioketone or thioenol forms. Both mono- and bis-ligand metal complexes as well as bis-metal complexes of the general formulae: [(H2daL)M]2+, [(daL)M], [(HmaL)2M]2+, [(maL)2M], [(HmaL)2MX2], [(H2daL)M2X4] and [(daL)M2X2] were prepared. All compounds under investigation were characterized and some of their physicochemical properties are reported. This revised version was published online in June 2006 with corrections to the Cover Date.     

Heteroorganic derivatives of furan. 68. Calculation and interpretation of the vibrational spectra of furan derivatives of group IVB elements

The frequencies and forms of the normal vibrations for trimethyl(2-furyl)silane, trimethyl(2-furyl)germane, and trimethyl(2-furyl)stannane molecules were calculated. An interpretation of the results of an experimental investigation of the vibrational IR absorption spectra and the Raman spectra of compounds with the formula R_nMMe_4–n(R=2-furyl, M=Si, Ge, Sn; n=1–4) is given.See [1] for Communication 67.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1184–1200, September, 1989.     

Synthesis, properties and crystal structures of ferrocene derivatives containing pyrazinium and quinoxalinium units

The pyrazinium salt [FcCH₂pyz][BF₄] (1) and the quinoxalinium salt [FcCH₂quin][BF₄] (2) were prepared by the reaction of [FcCH₂][BF₄] with pyrazine and quinoxaline, respectively and characterised by spectroscopic methods, cyclic voltammetry and by single-crystal X-ray diffraction, which revealed the absence of any π-π-stacking motifs in the crystal structures.     

Organosilicon compounds of the furan series. VI. Nitrogen- and sulfur-containing organosilicon derivatives of furan

Five new furfurylaminoorganylsilanes and furfurylaminoalkyltriorganylsilanes are synthesized by reacting furfurylamine with organylchlorosilanes, chloroalkyltriorganylsilanes, and triorganylhydrosilanes. Furfuraldoxime readily reacts with triorganylchlorosilanes in the presence of triethylamine to give O-triorganylsilyl substituted oximes. It is shown for the first time that in the presence of H₂PtCl₆ aldoximes undergo dehydrocondensation with triorganylsilanes, accompanied by reduction processes. Reaction of hexamethyldisilazane with pyromucamide gives the trimethylsilylamide. Pyromuconitrile and magnesium 3-(methyldiethylsilyl)propyl chloride gives 1-furyl-4-(methyldiethylsilyl)butanone-1. Reaction of organylchlorosilanes with furfurylmercaptan and sodium furfurylmercaptide permits synthesis of the first representatives of the sulfur-containing organosilicon derivatives of furan.Part V, see [1].     

Synthesis and anti-brucella activity of some new 1,3,4-oxadiazole derivatives containing a ferrocene unit

An isocyanide-based multicomponent reaction between cinnamic acid derivatives or 3-phenyl-2-propynoic acid, (N-isocyanimino)triphenylphosphorane, ferrocenecarbaldehyde, and dibenzylamine has been reported in excellent yields for the preparation of some new ferrocenyl-containing 1,3,4-oxadiazole derivatives. The anti-brucella activities of the products are investigated in in vitro and in vivo assays.     

Nuclear magnetic resonance spectra of furan derivatives of IV B group elements (review)

Electronic and steric effects in furan derivatives were studied by the method of ¹H, ¹³C, ¹⁷O, and ²⁹Si NMR spectroscopy. The characteristic features of the influence of substituents on the screening and spin-spin interaction of ring nuclei in -substituted derivatives of furan in the presence of a second -substituent have been noted.Dedicated to Prof. A. R. Katritsky on his 65th birthday.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 879–890, July, 1993.