Chromatography of organic derivatives of group IVB elements

Chromatographic aspects of the analysis of Group IV organometallic derivatives are reviewed. The emphasis is towards gas and liquid chromatography.     

High resolution NMR studies of allylic derivatives of group IVB elements

The high resolution NMR spectra of certain Group IVB allyl compounds, FC₃M(CH₂)_nCHCH₂R′ (where R = Me, Et, Ph; R′ = H, Ph; M = Sn, Si, Ge; n = 1 or 2), have been studied in an attempt to detect manifestations of ground state p_πd_π overlap. Analyses, using sub-spectral techniques for ABMX₂ and ABX₂ systems, were confirmed using computer iteration methods. The emphasis has been placed here on the sensitivity of the coupling constants of the allyl group towards anticipated steric and electronic perturbation or towards the interaction between the Group IVB atom d orbitals and the olefinic p_π orbitals. Some ¹¹⁹Sn chemical shifts have also been recorded. The conclusions reached do not support the existence of ground state d_πp_π overlap in these compounds.     

Mass spectra of monohapto-cyclopentadienyl derivatives of group IVB elements

Dissociative ionisation of organometallic cyclopentadiene derivatives containing one, two or three M(CH₃)₃ groups (M  Si, Ge, Sn) has been studied.Among the monometallated compounds, C₅H₅Si(CH₃)₂Cl, C₅H₅Si(CH₃)₂OCH₃ and (C₅H₅)₄Sb have also been investigated. To verify fragmentation patterns, the spectra of deuterated compounds such as C₅D₅Si(CH₃)₃, C₅D₅Sn(CH₃)₃, C₅D₄Si₂(CH₃)₆ and C₅D₃Si₃)₉ have been measured. Dissociative ionisation of h¹-cyclopentadienyl derivatives has been shown to differ essentially from that of h⁵-compounds.     

Mass-spectrometric study of permethyl compounds of group IVB elements

Russian Chemical Bulletin -     

Doping of group IVB elements for nickel-rich cobalt-free cathodes

Hetero-element doping is a promising strategy to improve the cycling stability of nickel-rich cobalt-free cathodes for the next-generation high energy-density Li ion batteries.To make doping effective,it is important to understand the mechanism of how the dopants regulate the electronic band,lattice parameter adjusting,or hetero-phase formation to achieve high stability.In this study,we investigate LiNi_0.9Mn_0.1O₂ cathodes doped with IVB grouping elements via mult...     

Vibrational spectra of the hexaalkyldielementooxanes-derivatives of the group IVB elements

Conclusions On the basis of the calculation of the frequencies and form of the normal vibrations for hexaalkyldielementooxanes (C₂H₅)₃MOM(C₂H₅)₃ (M is an element from the Group IVB) and the existence of a correlation between _as ^MOM and k_MO and _OH, it is shown that a change in the frequency of the antisymmetrical valence vibrations for the M-O-M group is mainly due to dynamic effects in the M-O-M system.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1042–1044, May, 1976.     

Substituent effects on the gas phase basicities of acetophenones

The gas phase basicities of m- and p-substituted acetophenones have been determined by the ion cyclotron resonance (ICR) equilibrium constant method. The application of the LArSR Eq. to these substituent effects provides a ϱ=12.2 and an r⁺=0.76 with excellent precision.     

Silylamides of group IVA and IVB elements with spirobicycloheptane structure

Spirocyclic metal silylamides with spiro[3.3]heptane structure, M′  Si, Ge, Sn, Ti, Zr and Hf, have been prepared. Except for the Si derivative, the synthesis involved

the reaction of the appropriate M′Cl₄ with Me₃SiN(M)SiMe₂-N(M)SiMe₃, M  Li, Na. The M′  Si derivative was obtained via reaction of IIIb with NH₃, subsequent treatment with butyllithium and Me₃SiCl, and then ring closure with Me₂SiCl₂. The new compounds have been characterized by analyses, NMR, IR, Raman and mass spectra. The metallaspiranes are thermally stable to > 200°C, are very volatile, and do not form complex with ether.     

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.     

Heteroorganic derivatives of sulfur-containing heterocycles. 28. Calculation and interpretation of vibrational spectra of thienyl derivatives of group IVB elements

The frequencies and forms of the normal vibrations were calculated for trimethyl(2-thienyl)-substituted silane, germane, and stannane molecules. An interpretation of the results of an experimental study of the IR spectra and Raman spectra of compounds with the general formula R_nMMe_4–n (R=2-thienyl, M=Si, Ge, Sn, n=1...4) is given.See [1] for communication 27.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1467–1482, November, 1989.     

Extractive separation of group IVB elements: analysis of alloy samples

A method is proposed for the extraction and mutual separation of quadrivalent titanium, zirconium and hafnium from hydrochloric acid using triphenylphosphine oxide dissolved in toluene as an extractant. The optimum conditions for the extraction and separation have been evaluated from critical study of acid concentration, extractant concentration, period of equilibration and effect of diluent. The effect of foreign ions on the extraction and determination is also discussed. The probable composition of the extracted species has been deduced from logD-logC plots. The method affords mutual separation of titanium, zirconium and hafnium and is applicable to the analysis of alloy samples.     

Charge control in the formation of complexes of phenol with ethylene derivatives containing organoelemental group IVB substituants

The v(OH) frequency shifts of phenol and the v_R resonance components of these shifts in the IR spectra of phenol H-complexes with ethylene derivatives containing various substituents including organosilicon, organogermanium, and organotin groups have been studied. The relationship between v and v_R and the values that characterize the influence of substituents on the effective charges of the double bonded carbon atoms was established; the latter values have been calculated previously usingab initio quantum chemical methods. The effective charges for the compounds with organoelemental substituents have been calculated. It has been elucidated that of the two types of possible interactions, charge controlled and orbital controlled, occurring in the formation of a complex of a hard acid, phenol, with the studied ethylene derivatives, the former is predominant.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1383–1387, August, 1993.     

Theoretical studies on vibrational spectra of some halides of group IVB elements

The vibrational spectra of group IVB elements halides MX4 (M=Ti(IV), Zr(IV), Hf(II); X=F, Cl, Br and I), have been investigated by ab initio RHF, MP2 and density functional theory B3LYP method with LanL2DZ basis sets. The optimized geometries, calculated vibrational frequencies and Far-IR intensities of MX4 are evaluated via comparison with experimental data. The vibrational frequencies, calculated by these methods, are compared to each other. The results indicate that B3LYP method is more reliable than RHF and MP2 methods for the frequencies calculations for these compounds. With this method, some vibrational frequencies of M2X6(2+)(M=Ti(IV), Zr(IV) and Hf(II); X=F, Cl, Br and I) are also predicted.     

Comprehensive density functional theory study on serine and related ions in gas phase: conformations, gas phase basicities, and acidities

Density functional theory (DFT) calculations have been performed to investigate the gas-phase conformations of serine and its three related ions (serineH(+), serine(-), and serine(2-)). The full ensemble of possible conformations, 324 conformations for serine, 108 for serineH(+), 162 for serine(-) and 54 for serine(2-), were first surveyed at B3LYP/6-31G level, and then the obtained unique conformations were further refined at B3LYP/6-311+G level. From full optimizations, 74 unique conformations for seine, 14 for serineH(+), 11 for serine(-), and 4 for serine(2-) were located, and their relative energies were also determined at B3LYP/6-311+G level. Atoms in molecules (AIM) analysis was carried out to establish rigorous definition of hydrogen bonds. Six types of intramolecular H-bonds in conformers of serine, six types in serineH(+), three types in serine(-), and two types in serine(2-) were identified within the framework of AIM theory and their relative strengths were determined based on topological properties at bond critical points (BCPs) of H-bonds. The intramolecular H-bonds were demonstrated to play an important role in deciding the relative stability of conformations of amino acids and the related ions. The enthalpies and Gibbs free energies of protonation and deprotonation reactions of serine and its related ions were calculated at B3LYP/6-311+G//B3LYP/6-31G, and B3LYP/6-311+G//B3LYP/6-311+G level. The calculated results are both in excellent agreement with the experimental data. We demonstrate in this study that B3LYP is an efficient and accurate method to predict the thermochemical and structural parameters of amino acids and the related ions.