Mass spectra of Si-substituted silatranes

Conclusions The mass spectra of a number of Si-substituted silatranes were studied and their dissociative ionization paths were discussed.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 626–628, March, 1979.     

Synthesis, structure, and complexing ability of hetarylhydrazones of glyoxylic acid

Benzoxazolyl-, benzthiazolyl-, 2′-quinolinyl- and 1′-phthalazinylhydrazones of glyoxylic acid (H₂L) and their complexes have been synthesized. The acid-base properties of the obtained hydrazones were studied by the methods of potentiometric titration and spectrophotometry. The hydrazones were shown to form mononuclear octahedral complexes M(HL)₂ with Ni(II) and Mn(II) acetates, whereas with Zn(II) and Cu(II) acetates binuclear complexes M₂L₂ were formed. The nature of the exchange interaction between the Cu(II) ions is discussed.     

Synthesis,structure, and complexing ability of pyrrole-2-carbaldehyde ferrocenoylhydrazone

A new ligand system based on pyrrole-2-carbaldehyde and ferrocenecarboxylic acid hydrazide was synthesized. Its tautomerism and complexing ability with respect to ions of bivalent metals: zinc, cadmium, and palladium were studied. The structure of the synthesized compounds was investigated by means of the density functional theory (DFT) calculations and spectral methods.     

The complexing ability of crown ethers incorporating glucose

The complexing (in CHCl₃) and extracting abilities of 18-crown-6 type compounds (1–15) were measured with Li, Na, K and NH₄ cations. The substituents on the sugar part affected these properties significantly (K _a=10³–10⁷). Some substituents, like acetyloxy groups (3) decreased whereas others, like tosyloxy groups (10, 11) significantly increased the complexing ability and thus changed the selectivity. The compound with four tosyloxy groups (11) shows an excellent picrate salt extracting ability in a CH₂Cl₂-water system.     

Proton magnetic resonance of some Si-substituted silatranes in the presence of paramagnetic Ni2+ and Co2+ ions

Conclusions The paramagnetic shifts, induced in the PMR spectra of 1-chlorosilatrane, 1-chloromethylsilatrane, and 1-methylsilatrane by the complexes of-ethylimidazole with NiCl₂ and CoCl₂, indicates that the coordination of these compounds in solution with paramagnetic Ni²⁺ and Co²⁺ ions is accomplished with involvement of the nitrogen atom.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1457–1459, June, 1978.The authors express their gratitude to L. V. Baikalova for synthesizing complexes (IV) and (V).     

Atranes. II. Dipole moments and structure of silatranes

Possible steric configurations of 1-organyl- and 1-organoxysilatranes,, are considered. The dipole moments of six compounds of this type (X=CH₃, (CH₃)₂CH, CH₂=CH, C₆H₅, C₂H₅O, C₆H₅O) have been found experimentally to be extremely high, 5.3–7.1 D. They conclusively show that the silatranes contain a semipolar transannular coordinate bond SiN between the negatively charged 5 -covalent silicon atom in the middle of the planar SiO₃ group and the tetrahederal onium nitrogen atom.Part I, see [1].     

The molecular and electronic structure features of silatranes, germatranes, and their carbon analogs

Molecular geometries of fifty-six metallatranes N(CH₂CH₂Y)₃M-X and fifty-six carbon analogs HC(CH₂CH₂Y)₃M-X (M = Si, Ge; X = H, Me, OH, F; Y = CH₂, O, NH, NMe, NSiMe₃, PH, S) were optimized by the DFT method. Correlations between changes in the bond orbital populations, electron density ρ(r), electron density laplacian ∇²ρ(r), |λ₁|/λ₃ ratio, electronic energy density E(r), bond lengths, and displacement of the central atom from the plane of three equatorial substituents and the nature of substituents X and Y were studied. As the number of electronegative substituents at the central atom increases, the M←N, M-X, and M-Y bond lengths decrease, while the M←N bond strength and the electron density at critical points of the M←N, M-X, and M-Y bonds increase. An increase in electronegativity of a substituent (X or Y) is accompanied by a decrease in the ionicities of the other bonds (M-X, M-Y, and M←N) formed by the central atom (Si, Ge). A new molecular orbital diagram for bond formation is proposed, which takes into account the interaction of all five substituents at the central atom (M = Si, Ge) in atrane molecules. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 448–460, March, 2006.     

N-aryl-and N-vinyldiaza-18-crown-6: Synthesis and complexing ability

The nucleophilic aromatic and vinyl substitution using diaza-18-crown-6 as nucleophile afforded a number of its N,N’-diaryl-[aryl = 2,4-(NO₂)₂C₆H₃, 4-C₅F₄N, 4-CF₃C₆F₄] and N,N’-dialkenyl-substituted derivatives [alkenyl = PhC(O)CH=CH, MeOCOCH=CH, (EtO₂C)₂C=C(Ph), etc.]. Arylation of diaza-18-crown-6 with nonactivated aryl bromides, such as 4-Me₂NC₆H₄Br, 4-MeOC₆H₄Br, C₆H₅Br, and 4-CF₃C₆H₄Br, was effected under catalysis by palladium complexes. N,N’-Diaryldiaza-18-crowns-6 having electron-acceptor substituents in the aromatic rings turned out to be incapable of forming complexes with metal cations, while their analogs containing electron-donor para-methoxy and para-dimethylamino groups gave complexes with barium perchlorate.     

Synthesis,spectroscopic studies,and crystal structure of 2,6-diacetylpyridinediphenylhydrazone perchlorate and its complexing ability toward the lanthanides

2,6-diacetylpyridinediphenylhydrazone perchlorate was prepared and characterized by spectroscopic (IR, ESI–MS, UV–Vis, ¹H NMR) and analytical data and its crystal structure was determined by single X-ray analysis. The lanthanum(III), praseodymium(III), and neodymium(III) perchlorate complexes of 2,6-diacetylpyridinediphenylhydrazone were prepared in a direct reaction of the ligand with appropriate metal perchlorates. The spectroscopic and analytical data indicate 1:2 metal to ligand stoichiometry. In all the complexes the hydrazones act as monodeprotonated terdentate NNN donor chelators. The same lanthanum(III) complex was also obtained in a one-step condensation reaction between 2,6-diacetylpyridine and phenylhydrazine in the presence of lanthanum(III) perchlorate.     

The 15N NMR study of silatranes

Various silatrane compounds were studied by means of ¹⁵N NMR spectroscopy. The quantum chemical calculations of some of the compounds were carried out using CNDO/2 method. The following correlations were obtained, i.e., ¹⁵N chemical shifts vary linearly with Taft's polar substituent constants (s) of the substituents R on the silicon atoms, and also with the net charge densities on the nitrogen atoms. From both experimental and theoretical aspects, it could be concluded that the SiN dative bonds in a series of silatrane compounds actually exist.     

Synthesis, structure, and spatial arrangement of Si-substituted N-(dimethylsilylmethyl)imides

The synthesis of N-(chlorodimethylsilylmethyl)succinimide and N-(chlorodimethylsilylmethyl)-glutarimide by the reaction of the corresponding N-trimethylsilylimides with chlorodimethylsilane and by the reaction of unsubstituted imides with a mixture of hexamethyldisilazane with dimethylchloromethylchlorosilane is described. The formation of N-(chlorodimethylsilylmethyl)succinimide is followed by substitution by the silicon atom, which, depending on the reagent ratio, provides N-(dimethylsuccinimidomethyl)succinimide as the major or minor product. ¹H, ¹³C, and ²⁹Si NMR spectroscopy and X-ray diffraction analysis showed that the silicon atom in N-(chlorodimethylsilylmethyl)glutarimide is five-coordinate. By contrast, in N-(chlorodimethylsilylmethyl)succinimide and N-(dimethylsuccinimidomethyl)succinimide, according to NMR and X-ray diffraction data, the silicon atom is four-coordinate. Quantumchemical calculations by the AM1 method show that the molecular conformations of N-(chlorodimethylsilylmethyl)imides containing an intramolecular OSi bond are not energetically most favorable in the gas phase.Translated from Zhurnal Obshchei Khimii, Vol. 74, No. 10, 2004, pp. 1617–1623.Original Russian Text Copyright © 2004 by Pogozhikh, Ovchinnikov, Kramarova, Negrebetskii, Shipov, Albanov, Voronkov, Pestunovich, Baukov.This revised version was published online in April 2005 with a corrected cover date.     

An infrared study of the complexing ability of manganese phthalocyanine

The complexing ability of manganese phthalocyanine (MnPhc) in the solid state has been studied in detail using i.r. spectroscopy. It has been shown that in its α modification, MnPhc readily adsorbs phenol, pyridine and formic acid. Nothing happens with the β modification. The results have been compared to previous studies and they are explained in terms of valence bond model and molecular orbital model.     

Synthesis,photochromism, and complexing ability of new derivatives of N-aminofulgimide

On the basis of N-aminofulgimide two new photochromic compounds of the fulgimide class were synthesized. The performed spectral-kinetic studies have shown that the obtained fulgimide derivatives suffer thermally irreversible transformation similar to those observed for the starting N-aminofulgimide except for the absorption bands of the corresponding cyclic forms to undergo red shift. One of the obtained compounds is capable to form complexes with rare-earth metal ions.     

1'-Phthalazinylhydrazone of acetylferrocene: Structure,properties, and complexing ability

1'-Phthalazinylhydrazone of acetylferrocene (HL) and copper(II) and nickel(II) complexes on its basis [CuL₂] and [NiL₂] have been synthesized and investigated. The structure of the hydrazine was determined by X-ray diffraction analysis. Quantum-chemical simulation of the tautomerism of the hydrazone was performed.     

氮杂硅三环类化合物的质谱研究

本文对二十四个氮杂硅三环类化合物进行了质谱研究.测定了它们的低分辨质谱,收集了大部分化合物的高分辨质谱数据并进行了亚稳跃迁测定。结果表明,分子离子的稳定性、基峰的生成方式以及碎片离子的多少主要取决于取代基R的性质.分子的电子轰击质谱裂解存在三种基本方式:(1)断裂Si～R键,生成高度稳定的(M-R)~ 离子,碎片离子较少;(2)开环,失去碎片C_2H_3O;(3)开环,失去碎片CH_2O或CH_3O.用电荷自由基定域理论解释这类化合物的质谱裂解机理,并对影响分子离子稳定性的有关因素及影响基峰形成的原因进行了讨论.     

Triethynylsilane and some of its Si-substituted derivatives

Conclusions Triethynylsilane and some of its Si-substituted derivatives, corresponding to the general formula (HCC)₃SiX, where X=H, OCH₃, OCOCH₃, OSi(CH₃)₃, OSi(CCH)₃, were synthesized.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2147–2148, September, 1978.     

Dipole moments,structure, and transannular interactions in silatranes containing planar fragments

The method of dipole moments and theoretical calculations (DFT B3LYP/6-31G^*) were used for structural assessment of silatranes N[CH₂(RMeC₆H₂)O]₃SiR¹ containing planar fragments in the six-membered semirings. They are endo structures with transannular N→Si interaction which involves, along with nitrogen and silicon, oxygen atoms adjacent to silicon.     

Synthesis,structure, and complexing ability of a novel ligand system, 1-benzyl-2-benzimidazolylhydrazone of pyrrol-2′-carbaldehyde

A new ligand system, the product of condensation of pyrrol-2-carbaldehyde and 1-benzyl-2-hydrazinobenzimidazole is synthesized. Possible tautomers of the hetarylhydrazone are calculated and its acidebase properties studied, as well as its complexing ability with respect to divalent ions of copper, nickel, zinc, and chromium.