Specific C-H...N intramolecular interaction in 1-vinyl-2-cyanoethylthiobenzimidazole with the formation of a nine-membered intramolecular ring,according to1H and13C NMR data

In the¹H NMR spectrum of 1-vinyl-2-cyanoethylthiobenzimidazole, an abnormal downfield shift has been found in the signal of the -hydrogen atom of the vinyl group, and also an increase in the corresponding direct¹³C-¹H spin-spin coupling constant, in comparison with other 2-substituted benzimidazoles. This indicates a specific C-H...N intramolecular interaction in this molecule between the -hydrogen atom and the cyano nitrogen atom, forming a nine-membered intramolecular ring.Translated from Translated from Izvestiya Akademii Nauk SSSR No. 10, pp. 2285–2288, October, 1991.     

Molecular structure of a new palladium-containing vinylidene cluster [η2-Ph2P(CH2)3PPh2]PdFe3(μ4-C=CHPh)(CO)9

The structure of the vinylidene cluster [²-Ph₂P(CH₂)₃PPh₂]PdFe₃(₄-C=CHPh)(CO)₉ was established by X-ray diffraction analysis. The metal core of the molecule has a butterfly shape with the Pd atom occupying a wingtip position. The C(1)=C(2)HPh ligand is -bound to three atoms of the Fe₂Pd triangle through the C(1) atom and is ²-coordinated to the Fe atom located in the second wingtip position via the C(1)=C(2) double bond. The Pd atom is chelated by the diphosphine ligand.     

Multinuclear NMR (1H,13C,15N,17O) studies of intramolecular interactions in 1-vinylpyridones and quinolones

¹H and¹³C NMR was used to estimate the dihedral angles between the planes of the vinyl group and the hetero ring for 1-vinylpyridones and quinolones. The¹H,¹³C,¹⁵N, and¹⁷O NMR data showed the existence of a specific intramolecular weak hydrogen bond between the -H atom of the vinyl group and the O atom in 1-vinyl-2-pyridones and 2-vinyl-1-isoquinolone.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1539–1547, July, 1990.     

Spectroscopic effects and intramolecular interactions in the1H and13C NMR spectra of five-membered N-vinyllactams

In 1-vinylpyrrolidone, 1-vinyl-1,2,4-triazole-5-ones, 1,3-divinylimidazolidine-2-thione, and 1-vinylbenzimidazole-1-thione the vinyl groups exist predominantly in the s-trans-, but in 1-vinyl-4,5-diphenylimidazole-2-ones in the s-cis(0)-conformations relative to the exocyclic heteroatom. In 1-vinylbenzimidazole-2-ones, 3-vinylbenzoxazole-2-one, and 1-vinylindole-2,3-diones the vinyl group is present as a mixture of the s-cis(0)- and s-trans(0)-conformations. According to¹H and¹³C NMR results there are specific intramolecular interactions in 1-vinylpyrrolidone and in 1,3-divinylimidazolidine-2-thione resembling weak hydrogen bonding between the -hydrogen atoms of the vinyl group and the oxygen or the sulfur atom. In 1-vinylsuccinimide, 2-vinylphthalimide, and 1,3-divinyl-4,5-diphenylimidazole-2-one there is the same type of interaction with the -cis-hydrogen atom of the vinyl group, while in 1,3-divinyl-1,2,4-triazole-5-one there is interaction between the same hydrogen atom and the nitrogen atom.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 1983–1990, September, 1990.     

Synthesis, characterization and luminescence study of dimethyl[2-(arylmethyleneimino)phenolato]gallium complexes: Crystal structure of dimethyl[N-(4-N,N′-dimethylamino) phenylmethyleneiminophenolato]gallium

Three dimethylgallium complexes of type Me₂GaL [L = 2-methoxylphenylmethyleneiminophenolato (1), N-(4-N,N′-dimethylamino)phenylmethyleneiminophenolato (2), N-(2-naphthyl)methyleneiminophenolato (3)] have been synthesized by the reaction of trimethylgallium with appropriate N-arylmethyleneiminophenol. The complexes obtained have been characterized by elemental analysis, ¹H, ¹³C{¹H} NMR, IR and mass spectroscopy, respectively. The solid structure of 2 has been determined by X-ray single crystal analysis. The gallium atom was bonded by an oxygen atom and coordinated by an imine nitrogen atom forming one five-membered ring. The stable dimmer was formed by the coordination of bridging oxygen atom of phenolate to another gallium atom. The photoluminescence of complexes 1-3 were studied. The maximum emission wavelengths of 1-3 are between 305 and 320 nm upon radiation by UV light. The electroluminescent properties of diodes using 1-3 as emitting material were measured. The blue/green electroluminescence has been observed.     

Alpha-recoil atoms of plutonium in the environment

The -recoil effect of²³⁹Pu has been observed in environmental samples and theN ₅ ^P /N₅ ratio in these samples has been calculated. This ratio in atmospheric samples is in the range between 10^–5 and 10^–4 (atom/atom). For other contemporary terrestrial samples it is in the range between 10^–7 and 10^–6 (atom/atom), while that of uranium mineral is about 10^–10 (atom/atom). The results further explain the radioactive fallout contamination of our environment by uranium and plutonium isotopes.     

Structure of indolylphenylmethyl cations

The charge distribution in 1-methyl-2-carboxy-3-indolylphenylmethyl cation (II), which is formed by dissociation of the C-X bond in 1-methyl-2-carboxy-3-(-X-benzyl)indoles (I) in H₂SO₄ solution, was studied by PMR and¹³C NMR spectroscopy. Cation II may have a structure with a positive charge on the benzyl carbon atom (IIa), the nitrogen atom (IIc), or on the-carbon atom of the indole ring (IIc). Structures IIc and IIa make the major contributions to the II structure; this is confirmed by calculations by the Pariser-Parr-Pople (PPP) method within the- approximation.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 60–62, January, 1978.     

Photoelectron spectra and electronic structure of derivatives of imidazoline

We have obtained for the first time the photoelectron spectra (PES) of 20 diamagnetic and paramagnetic derivatives of imidazole. On the basis of calculations in the MNDO approximation, analysis of the vibrational structure, and comparisons in a series we have interpreted the bands in the range 7–11 eV. In the nitroxyl radicals of 3-imidazoline the highest occupied molecular orbital is the _NO ^* orbital, having also a contribution on the C⁴ atom. On introducing N-oxide groups there is a considerable rearrangement of the electronic structure of the radicals. In the PES of the nitroxyl radicals of 3-imidazoline-3-oxide there is multiplet splitting of the ionization band of the n_o·MO, amounting to 0.3–0.4 eV. Replacement of the methyl groups on the C² atom by methoxyl groups leads to an increase in the interactions of the unshared pairs of the O atoms of the nitronium and nitroxyl groups, while the same replacement on the C⁵ atoms leads to a considerable decrease in this interaction. When the substituent on the N¹ atom in derivatives of 3-imidazoline-3-oxide is varied the energy of ionization of the _C-NO MO decreases in the series: CH₃ < H OH < O < NO.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 8, pp. 1769–1777, August, 1990.     

Specific intramolecular C-H...O interactions in 1-vinyl-2-formylimidazole and 1-vinyl-2-formylbenzimidazole studied by1H and13C NMR spectral data

According to the¹H and¹³C NMR spectral data, the vinyl group in 1-vinyl-2-formylimidazole and 1-vinyl-2-formylbenzimidazole istrans-oriented with respect to the formyl fragment, while the carbonyl group occupies theanti-position with respect to the N atom of pyridine cycle. A specific intramolecular C—H...O interaction of a weak hydrogen bond type is realized between the -H atom of the vinyl group and O atom of the carbonyl group.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1197–1201, May, 1996.     

Cumulative author index

Reactions of L₂M(CO)X (L = Ph₃P, PhMe₂P, Ph₃As; M = Rh^I, Ir^I and X = Cl, Br, I) with

(n = 4 for R = R′ = CH₃; n = 2 for R = R′ = p-tolyl and for R = CH₃ and R′ = p-tolyl) afford the novel complexes

in which three-coordinate Cu^I is directly bonded to the five-coordinate metal atom M^I. The M^I→Cu^I donor bond is bridged by the azenido group. The halide atom X has migrated from the metal atom to the copper atom.Possible mechanisms for the formation of these complexes and of related new formamidine and trifluoroacetate compounds are considered and the properties of the complexes are discussed.     

Nitrogen-containing organosilicon compounds. 150. Synthesis and chromatographic and 1H, 13C, 15N,and 29Si NMR spectroscopic investigation of substituted (piperidinoalkyl)silanes

Substituted (piperidinoalkyl)silanes were synthesized and investigated by means of multinuclear NMR spectroscopy and GLC. The data obtained indicate an additional N-Si interaction in -aminomethylsilanes that depends substantially on the properties of the substituents attached to the silicon atom. The effect of the R¹R²R³Si substituent on the capacity of the nitrogen atom for intermolecular interactions is not restricted to steric effects but also has electronic character.See [1] for communication 149.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1644–1652, December, 1991.     

Mechanism of recoil implantation reactions of technetium and ruthenium in metal acetylacetonates

Recoil implantation of Tc and Ru in metal acetylacetonates were performed using ruthenium metal as a source and M^III/acac/₃ and M^II/acac/₂ complexes as catchers. The recoil atoms were obtained by¹⁰⁰Ru/, p/^99mTc and⁹⁸Ru/, n/⁹⁷Ru reactions. The yields of Tc/acac/₃ and Ru/acac/₃ were clearly dependent on the force constant of the bond between the central metal atom and oxygen in acetylacetone K/M–O/. A plot of the yield vs. 1/K(M–O) showed a linear relationship. However, the yield of Tc/acac/₂ implanted in M/acac/₂ did not show such a dependence on the force constant. The difference of the mechanism of complex formation between Tc/acac/₃ and Tc/acac/₂ was discussed on the basis of a reaction cage surrounding the recoil atom and of reaction time necessary for competition between the recoil atom and the central metal of the catcher complex.     

Synthesis and Reactions of Platinum(III) Complexes with Protoporphine Ligands in Mixtures of Acetic and Sulfuric Acids

Unusual stable platinum complexes (Cl)PtIIIP were obtained by the reaction of K₂[PtCl₆] with porphyrin H₂P (full methyl ethers of proto-, meso-, deutero-, and hematoporphyrin) in a 1:2 molar ratio in boiling pyridine. The forms of existence, kinetics and mechanism of dissociation of metal porphyrins in AcOH-(0.3-2.1) M H₂SO₄ mixtures were studied at 300-330 K. The reaction has first-order with respect to metal porphyrin, low E values (21-48 kJ/mol), and negative S values (-145- to -224 J mol^{- 1} K^{- 1}). The dependence of the formal first-order rate constants on H₂SO₄ concentration is linear at low values of this latter (up to 1.5 M). The mechanism of the electron density redistribution produced by functional substitution in positions of the macroring was studied to establish that the character of the dependence of the dissocia- tion rate on the macroring nature is determined by restricted -electron density transfer from the metal atom to a coordinated N atom.     

Spin density distribution in paramagnetic azafullerene

Hyperfine coupling (HFC) constants for ¹⁴N and ¹³C nuclei in azafullerene C₅₉N (1) were calculated. The HFC constants for the ¹H and ¹³C nuclei in the ^·CH₃ radical were calculated as functions of the pyramidal distortion of the angles at the carbon atom. Using this angular dependence, the spin density distribution of the unpaired -electron in 1 was determined. The spin density of the unpaired -electron in 1 is mainly localized around the nitrogen atom.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2372–2374, November, 2004.     

Fluorescent behavior of 2‐(3,4,5,6‐tetrafluoro‐2‐hydroxyphenyl)imidazo‐[1,2‐a]pyridine in the presence of metal perchlorate

2‐(3,4,5,6‐Tetrafluoro‐2‐hydroxyphenyl)imidazo[1,2‐a]pyridine ( 1 ) emits long wavelength light around 540 nm both in polar and in nonpolar solvents. Zn²⁺ perchlorate in acetonitrile causes the intermediate wavelength emission around 430 nm, which is ascribed to the species where the imidazole nitrogen atom and the phenolate oxygen atom bridge Zn²⁺. In the presence of Hg²⁺ and Al³⁺ perchlorates, short wavelength emission around 370 nm is strongly increased and this fluorescent enhancement is attributable not to the coordination of Hg²⁺ and Al³⁺ to 1 but to the formation of the salt of perchloric acid of 1 .     

1 H and 13 C NMR spectra and structure of 2-trichloromethyl-4-methylene-1,3-dioxolanes

The ¹H and ¹³C NMR spectra of a number of 5-substituted 2-trichloromethyl-4-methylene-1,3-dioxolanes were studied. It was observed that the exocyclic double bond is in effective conjugation with the 3–0 ring atom. The configuration of the substituents was established, and a conformational model of these heterocycles of the envelope type with the 1–0 atom deviating from the plane in which the remaining ring atoms are situated is proposed. The applicability of the ¹³C NMR spectra for the determination of the configuration of the compounds is demonstrated.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1176–1180, September, 1976.     

Theoretical Study of Chemical Binding of Noble Gas Atom and Transition Metal Complexes: Ng–NiCO, Ng–NiN2, Ng–CoCO (Ng = He–Xe)

Ab initio multireference and coupled cluster methods (MR-SDCI(+Q), CASPT2, CCSD(T)) and density functional theory methods (B3LYP, MPWPW91) have been applied to examine geometrical structures and vibrational frequencies of noble gas (Ng) – transition metal compounds, Ng–NiCO, Ng–NiN₂, and Ng–CoCO (Ng = He, Ne, Ar, Kr, Xe). It is shown that the respective compounds can have a larger binding energy than a typical van der Waals interaction energy. The binding mechanism is explained by a partial electron transfer from a noble gas atom to the low-lying 4s and 3d vacant orbitals of the transition metal atom. Theoretical calculations show that the binding of noble gas atom results in a large shift of the bending frequency: 361.1cm^–1 (NiCO) to 403.5cm^–1 (Ar–NiCO); 308.5cm^–1 (NiN₂) to 354.8cm^–1 (Ar–NiN₂); 373.0cm^–1 (CoCO) to 422.6cm^–1 (Ar–CoCO). The corresponding experimental frequencies determined in solid argon are 409.1cm^–1 (NiCO), 357.0cm^–1 (NiN₂), and 424.9cm^–1 (CoCO), which are much closer to the corresponding frequency of Ar–NiCO, Ar–NiN₂, and Ar–CoCO, respectively.     

Crystal structure and conformational analysis of 1-[N-(2-bromophenyl)]naphthaldimine

1-[N-(2-bromophenyl)]naphthaldimine (C₁₇H₁₂NOBr) (1) was synthesised and its crystal structure was determined. The compound 1 is orthorhombic, space group P2₁2₁2₁ with a=12.653(2), b=13.7311(14), Z=4, R=0.032 for 499 reflections I>2σ(I)]. There is an intramolecular hydrogen bond of distance 2.473(3) Å between the hydroxyl oxygen atom and imine nitrogen atom, the hydrogen atom essentially being bonded to the oxygen atom. Minimum energy conformation was calculated as a function of torsion angle θ (C10-C11-N1-C12) varied every 5 degrees. The optimized geometry of the crystal structure corresponding to the non-planar conformation is the most stable conformation in all calculations. The results strongly indicate that the minimum energy conformation is primarily determined by hydrogen-hydrogen repulsions between the ortho-hydrogen atoms on the aldehyde rings. Complementary IR, ¹H NMR and UV measurements in solution and in the solid state were carried out.     

Metal–thiosemicarbazone interactions. Synthesis of an iodo-bridged dinuclear [diiodobis(pyrrole-2-carbaldehydethiosemicarbazone)dicopper(I)] complex

Reaction of copper(I) iodide with pyrrole-2-carbaldehydethiosemicarbazone (Hptsc) in a 1:1 mole ratio in MeCN, followed by addition of one mole of Ph₃P, yielded a complex of empirical formula, CuI(Hptsc)(Ph₃P), whose X-ray structure determination has shown that it exists as an iodo-bridged dinuclear copper(I) complex, [Cu₂(-I)₂( ¹-S-Hptsc)₂(PPh₃)₂](1). The central kernel, Cu(-I)₂Cu forms a parallelogram with unequal Cu—I distances {Cu—I, 2.644(2), 2.707(2)Å} and bond angles {Cu—I—Cu, 70.72(7), I—Cu—I, 109.28(7)°}. Each Cu atom is further bonded to one S atom of Hptsc and one P atom of Ph₃P, thus completing tetracoordination. The Cu...Cu separation of 3.097(4)Å is close to the sum of the van der Waals radius of the Cu atom, 2.80 Å. Compound (1) involves relatively strong inter-dimer hydrogen bonding via hydrazinic and pyrrole ring hydrogens with sulfur and iodine atoms respectively of the adjacent dimer {N(1)H...S^#2, 2.50 Å; N(4)H...I^#3, 2.91 Å}. The complex represents the first report of a copper(I) dimer with a thiosemicarbazone.