Library

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • 1990-1994  (2,263)
  • 1920-1924
  • 1991  (1,167)
  • 1990  (1,096)
  • Inorganic Chemistry  (1,466)
  • Computational Chemistry and Molecular Modeling  (797)
Material
Years
  • 1990-1994  (2,263)
  • 1920-1924
Year
  • 1
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991), S. 19-29 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A procedure for identifying redundancy in the Cartesian force constant matrix is described, and a prescription is given for generating the entire matrix of second derivatives from the minimal set of information. A proof is supplied which demonstrates that the number of nonredundant rows corresponding to a symmetry unique atom is necessarily less than three if the atom is invariant with respect to a symmetry operation of the point group other than the identity or inversion. Furthermore, only one row is required if the atom lies on a threefold or higher-order rotation axis. An application of the procedure to the evaluation of harmonic force constants by numerical differentiation of gradient vectors is briefly described.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991), S. 31-45 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An intermediate neglect of differential overlap (INDO) model for elements of the second transition series is described. Values of exponents for the radial portion of the Slater basis atomic orbitals, the orbital ionization energies, and the beta (or bonding) parameters for these elements are reported. Use of the model to investigate equilibrium geometries, relative energy ordering of geometric isomers, spectroscopic transition energies, energy ordering of state wave functions of different symmetry, trends in dipole moments, and equilibrium stretching frequencies is reported. The results indicate that the INDO method is capable of yielding quality results for species containing atoms of the second transition series.
    Additional Material: 11 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991), S. 625-645 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The numerical properties of a two-dimensional integral representation [J. Grotendorst and E.O. Steinborn, Phys. Rev. A 38, 3857 (1988)] of the three-center nuclear attraction integral with a special class of exponential-type orbitals (ETO'S), the B functions [E. Filter and E.O. Steinborn, Phys. Rev. A 18, 1 (1978)] are examined. B functions span the space of ETO'S. The commonly occurring ETO'S can be expressed in terms of simple finite sums of B functions. Hence, molecular integrals for other ETO'S, like the more common Slater-type orbitals, may be found as finite linear combinations of integrals with B functions. The main advantage of B functions is the simplicity of their Fourier transform that makes the derivation of relatively simple general formulas for molecular integrals with the Fourier transform method possible. The integrand of the integral representation mentioned above shows sharp peaks causing, in the case of highly asymmetric charge distributions, slow convergence of the quadrature method used by Grotendorst and Steinborn. New quadrature schemes are presented that use quadrature rules based on Möbius transformations. These rules are well suited for the numerical quadrature of functions that possess a sharp peak at or near a single boundary of integration [H.H.H. Homeier and E.O. Steinborn, J. Comput. Phys., 87, 61 (1990)]. Numerical results are presented that illustrate the fact that convergence of the new quadrature schemes is about a factor two faster in case of highly asymmetric charge distributions.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991), S. 681-688 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An orbital transformation that minimizes the sum of the squares of the off-diagonal Hamiltonian elements between the singly excited configurations is described. The resulting single-excitations-adapted molecular orbitals (SEAMOS) are found to be very suitable for the description of electronic excited states. The test calculations on the singlet and triplet excited states of the N2, CO, and H2CO molecules are presented.
    Additional Material: 12 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 5
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991), S. 709-727 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A theoretical model based on physical, chemical, and biochemical mechanisms has been presented to evaluate the yields of DNA strand breaks (single and double) as a function of linear energy transfer (LET) or -dE/dx. Energetic heavy charged particles are considered explicitly to provide a general theory for low- as well as for high-LET radiation. There are three main features of the calculation: (a) track structure considerations for the energy deposition pattern, (b) three-dimensional structure of DNA molecules to provide information on the exact location of damage, and (c) a Monte-Carlo scheme to simulate the diffusion processes of water radicals. To avoid the complexities of a cellular medium, an aqueous solution of DNA is considered in the calculation. When the results of the calculations are compared with experimental measurements of the yields of strand breaks in mammalian DNA (exposed in a cellular complex), reasonable agreement is obtained. However, only those experimental data have been compared where there were no enzyme repair processes. The method of calculation has also been extended to study breaks in higher-order structures of DNA molecules such as chromatin. Specific limitations of the present model have been pointed out for making further improvements.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 6
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991), S. 767-786 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Electronic aspects of the catalytic mechanism of liver alcohol dehydrogenase (LADH) are studied with the help of ab initio analytical gradient SCF MO methods. Three points are considered: (i) role of the catalytic zinc; (ii) geometry and electronic structure of the transition state for the hydride transfer reactions; and (iii) factors affecting the energy gap for the hydride transfer step, namely, substrate binding to zinc, reaction field, and serine 48 effects on the potential energy profile. The coordination sphere of the catalytic zinc has been modeled with an ammonia molecule and two SH- groups; complexes with CH3O-, CH3OH, and CH2O have been studied; a (6, 2, 2, 2, 1/6, 2, 1/3, 2) basis set has been used for Zn++; a (5, 2, 1, 1/3, 2) was used for oxygen, carbon, and sulfur; and a (3, 1) was used for hydrogen atoms. The hydride step was studied with two model systems: pyridinium cation/1,4-dihydropyridine coupled to the CH3O-/CH2O reaction, and cyclopropenyl cation/cyclopropene coupled to the CH3O-/CH2O system. For the latter, the role of Ser48 has been studied at the supermolecule level. The calculation on the hydride transfer step has been done at a 4-31G basis set level. The results obtained shed new light on the sources of catalytic activity of liver alcohol dehydrogenases.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 7
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991), S. 839-849 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We present a treatment of chemisorption that uses the Green matrix of the surface and the admolecule, as well as a cluster calculation of a small surface cluster. Since full HF-SCF-band structures with nonlocal exchange are available now for larger systems for a couple of years, it is possible to treat the substrate surface and the admolecule on equal footing. This offers a natural way to solve the embedding problem. We have applied the formalism to the adsorption of H2 on beryllium and show that in contrast to cluster calculations there appears a binding, which is experimentally verified.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 8
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991), S. 211-226 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The electronic absorption spectra of 2-, 3-, and 4-vinylpyridines and 1,2-(2,3-dipyridyl), 1,2-(2,4-dipyridyl), 1,2-(3,4-dipyridyl), and 1,2-(4,4-dipyridyl) ethylenes have been investigated in polar and nonpolar solvents. A correlation has been made between the geometry of the molecule and the observed spectrum. Molecular orbital calculations have been carried out using the INDO/S—CI procedure and a limited geometry optimization. The solvent effect at the MO level has been calculated. MO calculations predicted the existence of nπ* transitions that were not observed experimentally. The wave functions of the different CI states were calculated. The experimental transition energy as well as oscillator strength corresponded satisfactorily with the calculated ones. The observed transitions were assigned according to the results of MO calculations.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 9
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991) 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 10
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991), S. 251-267 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: From the speculations of G. N. Lewis in 1916, [J. Am. Chem. Soc. 38, 762 (1916)], the spectral predictions of R.S. Mulliken [Nature 122, 505 (1928)], and the quantum mechanical treatment by E. Hückel [Z. Phys. 60, 423 (1930)], the three lowest states of molecular oxygen (3Σg-, 1Δg, and 1Σg+) remained spectroscopic elusives until Gerhard and Lisa Herzberg [G. Herzberg, Nature 133, 759 (1934); L. Herzberg and G. Herzberg, Astrophys. J. 105, 353 (1947); G. Herzberg and L. Herzberg, Astrophys. J. 108, 167 (1948)], precisely defined them by observed infared transitions. The excited singlets remained of interest mainly to atmospheric spectroscopists and astrophysicists, and research on these species was scarce. The discovery in 1963 by A.U. Khan and M. Kasha [J. Chem. Phys. 39, 2105 (1963)] of the simple chemical production of singlet molecular oxygens by the aqueous reaction of hydrogen peroxide and hypochlorite released an explosion of research on the neglected species. Fifteen research symposia and research treatises confirm the broad range of chemical activities of singlet oxygen. The extension to biological systems is now proceeding, with surprising evidence of involvement of natural processes, including the action of singlet oxygen in white blood cell phagocytosis.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 11
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991), S. 371-386 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We propose 10 desirable features or criteria for general purpose methods to be applied to the calculation of a range of spectroscopic properties. We discuss the second-order polarization propagator approximation (SOPPA) in light of these criteria by giving the actual computational expression used as well as a few numerical examples taken from the theory of NMR spectra (magnetic shieldings and spin-spin coupling constants). We demonstrate that SOPPA comes close to fulfilling these criteria.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 12
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991), S. 423-436 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A method for analyzing asymmetric top rovibrational bands displaying both blended and resolved features is described. The two-phase computational procedure uses a modified version of the asymmetric rotor-band contour program FASTPLOT to generate a preliminary set of upperstate spectroscopic constants. The parameters are subsequently refined by employing the assigned line-fitting formalism of the ASYROT program using both resolved and blended features. The technique is detailed in a comprehensive analysis of the ν17 band of pyridine. Inclusion of quartic centrifugal distortion constants was found to satisfactorily model a high-resolution (0.004 cm-1) spectrum of this band, yielding a standard deviation of 0.00137 cm-1. The variation in the rotational parameters with vibrational quantum number is examined in terms of possible weak rovibrational perturbations to the ν17 state. An ab initio calculation of the ν17/ν27 Coriolis coupling constant indicates the observed results are consistent with the interaction of these two vibrational states.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 13
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991), S. 521-521 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 14
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991), S. 173-181 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An original procedure has been developed to determine the eigenvalues and the eigenfunctions of quantum-mechanical many-body systems with a harmonic oscillator interaction. Exact solutions in the explicit form have been obtained for the case of systems containing three groups of identical particles. For the system containing two groups of identical particles, a solution in the adiabatic approximation has been obtained and compared with the exact one.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 15
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991), S. 229-229 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 16
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991), S. 233-233 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 17
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991), S. 331-344 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 18
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991), S. 1-2 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 19
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991), S. 93-113 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The excitation and ionization spectra of RuO4 and OsO4 are studied theoretically by the symmetry-adapted cluster (SAC) and SAC-CI theories. This is the attempt to assign whole of the spectra by ab initio calculations including electron correlations. In the ground state, electron correlations work to reduce the polarity of the M-O bond overestimated in the Hartree-Fock calculation. The Os-O bond is stronger than is the Ru-O bond, which is reflected in the differences of the excitation and ionization spectra of RuO4 and OsO4. The excitation energies of the experimental spectra are well reproduced by the SAC-CI theory, though the calculated intensities of some peaks are very small in comparison with the experiments. The outer-valence ionization spectra calculated by the SAC-CI theory agree well with the experimental photoelectron spectra. Some shake-up peaks that are accompanied with an electron-transfers from oxygen to metal are also calculated.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 20
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991), S. 159-162 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The dependence of the rainbow angle on the depth of the potential well, the equilibrium distance, andthe force constant of the potential are discussed for several potential functions.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 21
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991), S. 183-196 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An exact, within the Born-Oppenheimer approximation, body-fixed Hamiltonian for the nuclear motions of a triatomic system is presented. This Hamiltonian is expressed in terms of two arbitrarily defined internal distances and the angle between them. The body-fixed axis system is related to these coordinates in a general fashion. Problems with singularities and the domain of the Hamiltonian are discussed using specific examples of axis embedding. A number of commonly used coordinate systems including Jacobi, bond-length-bond-angle, and Radau coordinates are special cases of this Hamiltonian. Sample calculations on the H2S molecule are presented using all these and other coordinate systems. The possibility of using this Hamiltonian for reactive scattering calculations is also discussed.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 22
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 40 (1991), S. 1-2 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 23
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 40 (1991), S. 33-53 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A behavior of a quantum rigid and pointlike dipole in a permanent electric field is under study. A dependence of a number of librational energy levels on the strength of the electric field is investigated on the basis of some rigorous results for the appropriate normal Jacobian matrices.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 24
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 40 (1991), S. 139-148 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A very simple modification of the usual (∼N4) SCF procedure is proposed, permitting the exclusion of basis set superposition errors (BSSE) in problems of intermolecular interactions. No a posteriori corrections are required. The results of this “CHA/F method” are numerically close to those of the Boys-Bernardi correction scheme but are free from the “overcompensation” characteristic of the latter at smaller distances.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 25
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 40 (1991), S. 243-264 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The singly excited functions satisfying Brillouin theorem are expressed as linear combinations of configuration-state functions for any spin and spatial symmetries (atomic or molecular) and for any reference wave function. The generality of the formulation is ensured by the use of the irreducible tensor method that can be adapted to any symmetry point group of interest. The expansion coefficients are simply written as products of fractional parentage coefficients, spin- and orbit-recoupling coefficients, and phase factors. The formalism is illustrated for some atomic (Kh) and molecular (C∞v, C3v, and Td) configurations. Group theoretical techniques are also used to correlate the Brillouin conditions within a chain of groups.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 26
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 40 (1991), S. 299-304 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A model for catecholamine storage in vesicles is analyzed within the SCRF-CNDO/2 approach including continuum solvent effects. The model considers the approach of cationic norepinephrine (NE) to a positively charged guanidinium moiety. Ion-pair formation is found for the whole range of dielectric constants. Even though stable states of H-bonded partners are found for large dielectric constants, this process is ruled out to occur because it involves too high energies. It appears that the medium's polarity is determinant in lowering the energy barrier between the ion-pair complex and the separated partners. Thus, as the medium dielectric constant increases, the equilibrium between the two states is enhanced.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 27
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991), S. 519-519 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 28
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991), S. 487-517 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We present a general method of implementing the kinetic balance condition within the Dirac-Fock (DF) self-consistent field (SCF) formalism for closed-shell molecular structure. We review the steps leading to the derivation of DF SCF equations for closed-shell molecules, particularly as formulated by Matsuoka et al. In the present approach, the large component of the molecular spinors are expanded in terms of atomic basis spinors of spherical-type Gaussian functions, with the small component related to the large component by the kinetic balance condition. It is shown that imposing the kinetic balance condition on geometric Gaussian-type basis functions allows us to obtain the Fock matrix elements, involving both the large and the small components, form the standard nonrelativistic Cartesian-type matrix elements. By using properties of orthogonal polynomials, the solid spherical harmonics are expressed in Cartesian form, thus providing a general basis for transformation of one- and two-electron-matrix elements, obtained from a Cartesian Gaussian-type basis, to a spherical Gaussian-type basis. The advantages of using kinetically balanced geometric Gaussian-type basis functions in molecular DF calculations including finite-size nucleus effects are emphasized. For the sake of completeness, we have added in an appendix corrections to the nuclear attraction matrix elements for the finite-size nucleus already derived by Matsuoka.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 29
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Recently we extended our strategy for MRD-CI (multireference double excitation-configuration interaction) calculations, based on localized/local orbitals and an “effective” CI Hamiltonian, for molecular decompositions of large molecules to breaking a chemical bond in a molecule in a crystalline or other solid environment.Our technique begins with an explicit quantum chemical SCF calculation for a reference molecule surrounded by a number of other molecules in the multipole environment of more distant neighbors. The resulting canonical molecular orbitals are then localized, and the localized occupied and virtual orbitals in the region of interest are included explicitly in the MRD-CI with the remainder of the occupied localized orbitals being folded into an “effective” CI Hamiltonian. The MRD-CI calculations are then carried out for breaking a bond in the reference molecule. This method is completely general in that the space treated explicitly, as well as the surrounding space, may contain voids, defects, deformations, dislocations, impurities, dopants, edges and surfaces, boundaries, etc.Dimethylnitramine is the smallest prototype of the energetic R2N - NO2 nitramines, such as the 6-member ring RDX or the 8-member ring HMX. Decomposition of energetic compounds is initiated in the solid by a breaking of the target bond. Thus, it is crucial to know the difference in energy between breaking a bond in an isolated energetic molecule versus in the molecule in a solid. In the present study, we have carried out MRD-CI calculations for the Me2N - NO2 dissociation of dimethylnitramine in a dimethylnitramine crystal. The cases we investigated were one dimethylnitramine molecule (surrounded by 53 and 685 neighboring dimethylnitramine molecules represented by multipoles), three dimethylnitramine molecules, and three dimethylnitramine molecules (surrounded by 683 neighbors). All multipoles were cumulative atomic multipoles up through quadrupoles. The MRD-CI calculations on dimethylnitramine required large numbers of reference configurations from which were allowed all single and double excitations.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 30
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991), S. 667-679 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The frequency-dependent dipole polarizability, α(E), is calculated using the second-order polarization propagator approximation (SOPPA). We have shown how to express α(E) as a function of E2 and thus obtained a form of α(E) that can be used to compute C6-coefficients without invoking complex arithmetic. For He we find that SOPPA recovers a large fraction of the correlation contribution for all frequencies, whereas for H2 where the correlation contributions are much smaller and also basis set-dependent, we find a less definite trend of SOPPA relative to RPA.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 31
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991), S. 71-91 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The usefulness of the MS-Xα method for calculating molecular transition properties is investigated in a study of NO2. Two-dimensional potential surfaces are obtained in C2v symmetry for the X̃2A1/Ã2B2 system. Potential curves that approximately follow the asymmetric stretch coordinate are also presented: On investigation, no symmetry-broken solutions were found. At all nuclear geometries investigated, the muffin-tin sphere radii were chosen by an energy-minimization technique. The inclusion of corrections to the muffin-tin form of the Xα total energy is shown to be essential, if the computed surfaces are to be qualitatively correct. The transition dipole moment connecting the two states is evaluated as a function of nuclear coordinates, using the transition-state approximation. Finally, the radiative decay of a single vibronic level in NO2 is modeled and the relevance to experiment is discussed.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 32
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991), S. 131-147 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Nonempirical quantum chemical method Hartree-Fock-Roothan LCAO SCF MO in a two-exponent Dunning basis with the use of an extended set of Gaussian functions by Huzinaga-Dunning with consideration of electron correlation according to the Meller-Plesset theory of excitations of the second order was used to study monohydrates of Li+, Na+, K+, and HCOO- ions. The indicated basis was supplemented with polarization functions of d-type on the O atom and of p-type on the hydrogen atom as well as with diffusion functions of p-type on the oxygen atom. It has been found that binding energies of the water molecule with Li+, Na+ appeared to be higher and with K+ lower than with HCOO- · H2O. Potential curve shapes of K+ + H2O and HCOO- + H2O reactions are shown to be similar. The molecular mechanism of K+ channel selectivity of an excitable membrane is explained on the basis of the obtained calculations.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 33
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991), S. 287-298 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In flow tube studies of the quenching of O2(b1Σg+), broad band emission of O2(b):M collision complexes was found to appear under the discrete rotational lines of the 0-0 band of the b1Σg+ → a1Δg electric quadrupole transition at higher oxygen pressures and on addition of foreign gases. Bimolecular rate constants for the collision-induced emission processes have been derived from the ratio of the intensities of the discrete lines and the continuum as well as from low-resolution measurements of the relative intensities of the b → a and b → X bands as a function of O2 and added gas pressure. They range from ≈10-21 cm3 s-1 for He to ≈4 × 10-19 cm3 s-1 for PCl3 vapor.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 34
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991), S. 523-539 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We present a model system for the study of curve-crossing situations in diatomic molecules. All model parameters are determined by the potential energy topology. No coupling functions are fitted. The standard approximation schemes (Born-Oppenheimer approximation, adiabatic approximation, and the generator coordinate approximation) are then applied. The result of these numerical experiments suggest that the generator coordinate approximation is able to remove 80%-90% of the nonadiabatic effect on all levels throughout the crossing region.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 35
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991), S. 593-604 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An expression for the product of a single-cycle class [(1)N - P(p)]N and an arbitrary class [(1)l1(2)l … (N)lN]N of the symmetric group has recently been conjectured. This expression involves a sum over a relatively small number of reduced class sums, depending on p indices. A further conjecture is formulated and demonstrated, according to which reduced class coefficients (RCCS) involving cycles whose length is expressed by means of a single index can be related to corresponding coefficients in the product of [(1)N - P+1(p - 1)]N with an arbitrary class sum. Consequently, the problem of evaluating the general class sum product reduces to that of obtaining a relatively small set of fundamental RCCS containing no single-index cycles. The conjectures mentioned can be used to evaluate the product [(1)N - p(p)]N · [(1)N - q(q)]N in terms of fundamental RCCS that can all be obtained from the product [(r)]r · [(r)]r, where r = min(p, q). For the latter product, we use a result due to Boccara.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 36
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991) 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 37
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991), S. 647-647 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 38
    ISSN: 0009-2940
    Keywords: Manganese-mediated cyclization ; Nine-membered carbocycles ; Manganese complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Photochemical Reactions of Transition Metal Organyl Complexes with Olefines, 31). - [4 + 5] Cycloaddition of Conjugated Dienes to Tricarbonyl(η5-2,4-dimethyl-2,4-pentadienyl)manganeseTricarbonyl(η5-2,4-dimethyl-2,4-pentadienyl)manganese [1] reacts photochemically with the acyclic conjugated dienes 1,3-butadiene [A], 2-methyl-1,3-butadiene [B], (E)-1,3-pentadiene (C), (E,E)-2,4-hexadiene (D), 2,4-dimethyl-1,3-pentadiene (E), 2,4-hexadien-1-ol (F), and methyl 2,4-hexadienoate (G) in a formal [4 + 5] cycloaddition to give tricarbonylmanganese complexes with η3:2-2,6-cyclononadien-1-yl ligands (2A-2G). In addition, the reaction of 1 with A yields thermolabile [η3:2:2-1-(3-butene-1,2-diyl)-1,3-dimethyl-2,6-cyclononadiene]dicarbonylmanganese (3A) and E,E and E,Z isomers of [η3-1-(2-butene-1,1-diyl)-1,3-dimethyl-2,6-cyclononadiene]tetracarbonylmanganese (4A, 4A] as byproducts. Similarly, 1 reacts with B to form tetracarbonyl[η3-1-(3-methyl-2-butene-1,1-diyl)-1,3,6-trimethyl1-2,6-cyclononadiene]manganese (4B) in a side reaction. The crystal and molecular structures of tricarbonyl(η3:2-1,3,5,5,7-pentamethyl-2,6-cyclononadien-1-yl]manganese (2E) and of 3A are determined by X-ray structure analyses. In each of the formally octahedral complexes unusual long manganese-carbon bonds are found for one coordinated CC double bond of the hydrocarbon ligands.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 39
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 17-23 
    ISSN: 0009-2940
    Keywords: (Borole)nickel complexes ; Nucleophilic substitution at boron ; 1H-Borole ; Dihydro-1H-borolediide ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Derivatives of Borole, XVI1), - Bis(borole)nickel Complexes2)The dilithium 1-(dialkylamino)dihydroborolediides Li2[C4H4-BNR2] 2a, b: R = Me, Et) react with NiCl2 · DME to give bis(borole)nickel complexes Ni(C4H4BNR2)2. Nucleophilic substitution reactions are used to produce a large variety of derivatives Ni(C4H4BR)2 1 (e.g. R = H, tBu, F, Cl, Br, I, OH, OMe). Treatment of Ni(C4H4BCl)2 (tg) with LiO(CH2)3OLi in THF produces a polymer and a dinuclear complex (μ-{η5:η5-[(CH2)3(OBC4H4)2]}2Ni2 (3) which crystallizes from CH2Cl2 as solvate 3 · CH2Cl2. The complexes 1g and 3 · CH2Cl2 are characterized by X-ray diffraction work. Barriers to internal ring-ring rotation are measured by variable-temperature NMR spectroscopy. The B - H bond of Ni(C4H4BH)2 (1a) is remarkably inert and does not react with H2O or with carboxylic acids in THF at room temperature. With PhCHO slow formation of the benzyloxy compound Ni(C4H4BOCH2Ph)2 (1 m) is observed at 100°C. For typical complexes such as the phenyl derivative 1e cyclic voltammetry in CH2Cl2 reveals an irreversible oxidation at 1.32 and a quasi-reversible reduction at -1.37 V vs. SCE.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 40
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 25-29 
    ISSN: 0009-2940
    Keywords: Borole complexes ; {η5-[1-(Diisopropylamino)borole]}metal complexes, internal rotation of, protonation of ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Derivatives of Borole, XVII1). - {η5-[1-(Diisopropylamino)borole]}metal Complexes: Syntheses, Protonation, Internal RotationNew complexes M(CO)4L (M = Cr, W), cis-M(CO)2L2 [M = Mo, W (not isolated)], and (COD)NiL have been prepared from the Diels-Alder dimer L2, where L is 1-(diisopropylamino)borole, C4H4BNiPr2. Complexes of L can be protonated at the nitrogen atom to give stable salts such as [Cr(CO)4(LH)]BF4, [Fe(CO)3(LH)]BF4, [(C6Me6)Ru(LH)]BF4, and [CpCo(LH)]BF4; B  -  N bond dissociation is not observed. Barriers to internal rotation have been determined by variable temperature NMR spectroscopy for Cr(CO)4L, (COD)NiL, and NiL2. Three processes have been identified: rotation of the NiPr2 group around the B  -  N bond, gear-mesh rotation of the isopropyl groups around the C  -  N bonds, and rotation of L with respect to the counter ligands.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 41
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 51-61 
    ISSN: 0009-2940
    Keywords: Selenocarbonyl compounds, perfluorinated ; 1,3-Diselenetanes, perhalogenated ; 2-Selenabicyclo[2.2.1]hept-5-enes ; 1,3-Diselenetan-2-ylium hexafluoroarsenates ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Preparation of (Perfluoroalkyl)halogeno-1,3-diselenetanes from the Corresponding Selenocarbonyl Fluorides and Reactions with Boron Trichloride or Arsenic Pentafluoride1)Reactions of Hg(SeRt)2 (Rt = C2F5, C3F7, CF3) with (C2H5)2 All or All3 in octamethylcyclotetrasiloxane produce the unstable perfluoroalkaneselenocarbonyl fluorides 1 [R1 = CF3 (1 a), C2F5 (1 b), CF3Se (1 c)]. These compounds are very reactive and polymerize to rubberlike products. On heating the polymers decompose almost quantitatively to the monomers or dimers. In CFCl3 solution 1 dimerizes at 20°C in sunlight to the corresponding cis/trans-1,3-diselenetanes 2. The structure of 2 b is determined by single crystal X-ray diffraction. Different selenocarbonyl derivatives add to unsymmetrically substituted 1,3-diselenetanes 3. 1 a and 1 b react with cyclopentadiene to form the [4 + 2] cycloaddition products 4a and 4c. Halogen exchange reactions take place between 2a  -  d and BCl3. The cis-isomers react much faster than the trans-isomers to give a mixture of cis-, trans-forms of 5. When 2c,d is treated with BCl3 it is possible to isolate and characterize the pure trans-isomer 2d, which is separated by preparative gas chromatography from 5c,d. Fluorine abstraction with formation of 1,3-diselenetan-2-ylium ions (6a  -  f) are accomplished by reactions of 2 or 3 with AsF5 in SO2.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 42
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 87-88 
    ISSN: 0009-2940
    Keywords: Alkylidenesulfur difluoride oxide ; Carbon-sulfur double bond ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Hg[C(COF) = SF2 = O]2 is prepared by the reaction of FCO — CH = SF2 = O with HgF2. This compound represents the third known example of an alkylidenesulfur difluoride oxide. Its molecular structure is the same as that of the most abundant of the three isomers of FCO-CH = SF2 = O. This is assumed to be the result of weak intramolecular Hg… O contacts. With the exception of the fluorine atoms bound to sulfur, all atoms lie approximately in one plane.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 43
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 103-109 
    ISSN: 0009-2940
    Keywords: Asteranes ; Cage compounds ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Asteranes, XXII1).  -  Synthesis of a Double Tetraasterane: Nonacyclo[10.8.0.02,11.04,9.04,19.06,17.07,16.09,14.014,19]eicosane1,4,5,8-Tetrahydronaphthalene-2,3-dicarboxylic anhydride (9) is dimerized by UV light in dioxane yielding four isomeric [2 + 2] adducts whose methyl ester derivatives are elucidated spectroscopically. The structures of the major products 14 and 16 have been confirmed by X-ray structure analysis. Degradation of the carboxylic groups of 14 afforded the title compound 5.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 44
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 157-162 
    ISSN: 0009-2940
    Keywords: Fluoro compounds, aromatic ; Nitrite exchange by fluoride ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of Aromatic Fluoro Compounds by Nucleophilic Exchange of Nitro Groups by FluorideThe synthesis of aromatic fluoro compounds from the respective nitro compounds by nucleophilic substitution of nitrite by fluoride is described. Reasonable yields in case of nonactivated nitro compounds are only obtained if the nitrite formed in the reaction is eliminated by acylation. 1-Fluoro-3-nitrobenzene (2) was obtained from 1,3-dinitrobenzene (1), and 1-fluoro-3,5-dinitrobenzene (9) as well as 1,3-difluoro-5-nitrobenzene (10) from 1,3,5-trinitrobenzene (8) in yields up to 92% by reaction of nitro compounds with potassium fluoride in sulfolane at 180 - 200°C in the presence of phthaloyl dichloride (6); 1,2-difluoro-4-nitrobenzene (12) was formed in 58% yield from 2,4-dinitro-1-fluorobenzene (11) in the presence of pyromellitoyl tetrachloride (13).
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 45
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 13-16 
    ISSN: 0009-2940
    Keywords: Diphosphines, tetrakis(diisopropylamino) ; Phosphinous anhydrides ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis and Structure of Bis[bis(diisopropylamino)phosphino]chalcogenidesPhosphorodiamidous chalcogeno-anhydrides [(R2N)2P]2X (R = Me2CH; X = S, Se, Te) (2a-c) have been obtained by insertion of elemental sulfur, selenium, or tellurium into the P-P bond of the corresponding diphosphane (1). The structure of 2a and 2c has been confirmed by an X-ray diffraction.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 46
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 31-38 
    ISSN: 0009-2940
    Keywords: Fluorosulfonium salts, reaction with nucleophiles ; (Perfluoroakyl)(dimethylamino)sulfonium salts, preparation and structures of ; Methoxysulfinyl hexafluoroarsenate, alkylation with ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: (Perfluoroalkyl)(dimethylamino)sulfonium HexafluoroarsenatesMeN = S(CF3)2 (5) is alkylated by Me3O⊕ AsF⊖6 to Me2N-S(CF3)⊕2 AsF⊖6 (4). From 5 and MeOSO⊕ AsF⊖6 (6) MeOS(O)-N(Me)S(CF3)⊕2 AsF⊖6 (7) is formed as a relatively stable primary product. Decomposition of 7 gives the expected 4 only in poor yield. Nucleophilic substitution of the sulfur-bonded fluorine in CF3SF⊕2 AsF⊖6 (8) by Me3SiNMe2 yields CF3S(NMe2)⊕2 AsF⊖6 (9). Similarly, (CF3)2CFSF⊕2 AsF⊖6 (10) reacts with dimethyl(trimethylsilyl)amine to give (CF3)2CFS(NMe2)⊕2 AsF⊖6 (11). The structures of 4 and 9 are elucidated by X-ray analyses, and the influence of the substituents on the bonding is discussed.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 47
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 63-67 
    ISSN: 0009-2940
    Keywords: Dinuclear gold complex ; Silyl complex ; Gold-gold interaction ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Transition-Metal Silyl Complexes, 361).  -  On the Question of Gold-Gold Interactions in Ph2P[CH2]t(2)PPh2-Bridged Dinuclear Gold Silyl ComplexesDinuclear silyl gold complexes of the type dppm(AuSiR3)2 (1) or dppe(AuSiR3)2 (2) are prepared by the reaction of dppm-(AuCl)2 or dppe(AuCl)2 with two equivalents of LiSi(aryl)3 or LiSi(SiMe3)3 The complex dppe[AuSi(SiMe3)3]2 (2 c) exhibits crystallographic inversion symmetry, and therefore the distance between both gold atoms is a maximum. In dppm-(AuSiPh3)2 (1b) a gold-gold interaction between both gold atoms is observed [Au  -  Au 316.80(3) pm].
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 48
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 149-156 
    ISSN: 0009-2940
    Keywords: Cyclobutene, ring-opening ; Poly Diels-Alder reaction ; Molecules, double-stranded ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cyclobutene Ring Opening: A Useful Reaction for the Synthesis of Double-Stranded MoleculesSyntheses and ring-opening reactions of the compounds endo-5a - e and 9a - c, all containing cyclobutene rings, are described. From these experiments it is concluded that compound 9a is a useful AB-type Diels-Alder monomer for the synthesis of well-defined double-stranded molecules. The stereochemistry of the adducts endo-4b and endo-5d is determined by X-ray structure analysis.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 49
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 175-184 
    ISSN: 0009-2940
    Keywords: α-Enones, regioselective 1,2-addition of dimethyl phosphite to ; Allylic rearrangement of dialkyl (1-hydroxy-2-alkenyl)phosphonates ; 1-Alkenylphosphonates, 3-acetyloxy- ; 1-Alkenylphosphonates, 3-hydroxy- ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reaction of Dialkyl Phosphites with α-Enones, I. - Synthesis and Allylic Rearrangement of Dimethyl (1-Hydroxy-2-alkenyl)- and (1-Hydroxy-2-cycloalkenyl)phosphonatesVarious β,γ-unsaturated α-hydroxyphosphonates 3 are prepared in good yields by NaOCH3-catalyzed regioselective 1,2-addition of dimethyl phosphite to acyclic and cyclic α-enones at -35°C. On acid-catalyzed acetylation, the allylic α-hydroxyphosphonates 3 (R1, R2 + H) rearrange under thermodynamic control; yielding the new 3-acetyloxy-1-(cyclo)alkenyl derivatives 8, from which the transposed allylic alcohols 11 are readily obtained. Using shorter reaction times, acetylation of compounds 3 affords mixtures of 1- and 3-acetylated products, 10 and 8, respectively.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 50
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 207-212 
    ISSN: 0009-2940
    Keywords: 2,3,6-Trioxypentafulvenes ; Keto-enol tautomerism ; Push-pull system ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Syntheses of 2,3,6-trioxypentafulvenes with a free position at the ring are described, in which the protection of the C-3 hydroxy group as methoxy or acetoxy derivative has been required. The difference in the behavior of the title compounds in relation to the previously reported 1,4-disubstituted 2,3,6-trihydroxypentafulvenes 2a-e, which only exhibit enol forms, is discussed and attributed to the disappearance of the push-pull system formed by the C-3 enol group and the C-4 electron-withdrawing substituent.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 51
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 233-235 
    ISSN: 0009-2940
    Keywords: Hexaoxacyclotriacontadodecaenes ; Macrocycles ; 2,2-Bis(2-furyl)propane ; 2,5-Bis[1-(2-furyl)-1-methylethyl]furan ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: New O6 Macrocycles with 2,2-Bis(2-furyl)propane UnitsThe macrocycles 3a and 6 are prepared in 29 and 16% yield by cyclization of dilithiated 2,2-bis(2-furyl)propane (1) and 2,5-bis[1-(2-furyl) 1-methylethyl]furan (5), respectively, with ethyl N,N-dimethylcarbamate (2).
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 52
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 237-240 
    ISSN: 0009-2940
    Keywords: Bicyclo[3.2.1]oct-6-yl cations ; Wagner-Meerwein rearrangements ; Alkyl-bridged ions ; Conformational effects ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Rearrangements of 1,4,4- and 2,2,5-Trimethylbicyclo[3.2.1]oct-6-yl Cations1,4,4-Trimethylbicyclo[3.2.1]oct-6-yl cations (18) are generated from the tosylhydrazone 7, by nitrous acid deamination of the amines 6 and 8, and by acetolysis of the brosylates 21 and 24. The product distributions are but slightly affected by the configuration (exo vs. endo) of the leaving groups. The predominant product, 1,4,4-trimethylbicyclo[3.2.1]octan-exo-6-ol (11) is formed without significant redistribution of a 6-2H label. The degenerate Wagner-Meerwein rearrangement of the parent bicyclo[3.2.1]oct-6-yl cation is virtually eliminated by the presence of two methyl groups at C-4. Enhanced conformational strain, raising the barrier to ring flipping, accounts for these observations. Minor products (12, 13) arise from a 7,6-hydride shift of 18, followed by Wagner-Meerwein rearrangement. When the 2,2,5-trimethylbicyclo[3.2.1]oct-6-yl cation (19) is generated directly from the tosylhydrazone 17, the tertiary alcohol 13 is obtained as the major product. The conformational barrier to Wagner-Meerwein rearrangement is compensated by the incipient stabilization of the tertiary carbocation 20.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 53
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 403-405 
    ISSN: 0009-2940
    Keywords: 1,2-Dihydropentalenes ; 1,5-Dihydropentalenes ; Rearrangements ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An efficient one-pot synthesis of 3-substituted 1-phenyl-1,2-dihydropentalenes from α,β-unsaturated ketones is described. These compounds can be rearranged to their 1,5-dihydro isomers using different methods such as acid catalysis and vacuum-flash thermolysis or by chromatography on alumina.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 54
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 417-421 
    ISSN: 0009-2940
    Keywords: Methylenephosphines ; Voltammetry, cyclic ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Electrochemical investigations on a selection of methylenephosphines 1 and related systems are reported. They are shown to possess an irreversible oxidation and reduction wave. An exception is diaminodiphosphene, which reversibly forms a radical anion. A relative ordering of frontier orbitals is possible, based on the redox properties of these systems.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 55
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 321-327 
    ISSN: 0009-2940
    Keywords: Trifluororthocarbonates of potassium, rubidium, cesium ; Phase transitions ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Crystal Structures of Potassium, Rubidium, and Cesium Trifluororthocarbonate and a Remark Concerning the Barium Sulfate Type1)Crystals of potassium, rubidium, and cesium trifluororthocarbonate (9a, 9b, and 9c) have been grown by Ostwald ripening in CH3CN applying a COF2 pressure of 3 bar. According to X-ray single-crystal structure analysis, 9a, 9b, and 9c belong to the baryte-structure family with an pseudotetrahedral anion being dynamically disordered at room temperature. All of the title compounds undergo a phase transition into a monoclinic, completely ordered low-temperature form, which has been refined for 9c. The C - O bond seems to be shortened by polar interactions. The results obtained with 9a, 9b, and 9c at room temperature indicate that the type of disorder found in 9 might be generally present in baryte-type compounds.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 56
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 339-345 
    ISSN: 0009-2940
    Keywords: Photoadditions ; Caffeine derivatives ; Calculations, AM1 ; Diradicals ; Propellanes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Selectivities in Photoadditions with Multifunctional Caffeine DerivativesElectronically excited stilbene (21*), 4,4′-dichlorostilbene (1*), and 4,4′-dimethoxystilbene (18*) are trapped by caffeine derivatives 2, 13, or 22 with variable results. While 1* and 2 react predominantly at the imino double bond (substitutive and fragmentating additions), 1* or 18* and 13 produce mostly propellanes by [2 + 2] photocycloaddition, which hydrolyze or may be hydrolyzed. 21* and the relatively electron-poor compound 22 produce mostly propellanes, which always show a preponderance of the syn-10, anti-11 stereoisomers. These selectivities as well as the competition with reactions at the imino double bonds are rationalized on the basis of diradical mechanisms with the aid of semiempirical AM1 calculations. Earlier results on closely related transformations are also discussed.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 57
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 377-381 
    ISSN: 0009-2940
    Keywords: Phosphorus compounds, organic ; Phosphorus heterocycles ; Arbuzov rearrangement ; Mechanism, SN2, SN1 ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Addition Reactions of Phosphorus Nucleophiles to BenzothieteTrialkyl phosphites 4 add to the o-quinoid form 2 of benzothiete (1) to yield the phosphonates 6. An intermolecular migration of an alkyl group from oxygen to sulfur is the most important feature of this transformation. The rearrangement - related to the Arbuzov reaction - can be avoided in a two-step process by the subsequent action of PCl3 and alcohol; thus the phosphonates 10 are generated. Analogous to 2 → 6, dimethyl phenylphosphinate (11) furnishes 13. In contrast, the cyclic esters 14a-d form 2:1 adducts, namely the 12- to 15-membered heterocyclic compounds 17a - d. An intramolecular rearrangement in a 1:1 adduct is only observed for the 1,3,2-dioxaphosphepine 14e, a benzylic system which allows an SN1 process generating the 1,6,2-oxathiaphosphecine 18e. A similar rearrangement at a tertiary carbon center is prevented by the competitive addition of water (1 + 14f → 20).
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 58
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 391-396 
    ISSN: 0009-2940
    Keywords: Ozonolysis ; Cycloalkylidenecycloalkanes ; Dispiro-1,2,4-trioxolanes ; Thermolysis ; Photolysis ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Dispiro-1,2,4-trioxolanes by Ozonolysis of Cycloalkylidenecycloalkanes on PolyethyleneOzonolyses of symmetrical (1b - d) and of unsymmetrical cycloalkylidenecycloalkanes (8a, b) afforded the dispiro-1,2,4-trioxolanes 4b - d and 9a, b, respectively. Their thermal decompositions gave mixtures of the cyclic ketones (3) and lactones (6). Photolyses afforded in addition to 3 and 6 the cyclic anhydrides 13, which are isomeric with the corresponding dispiro-1,2,4-trioxolanes.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 59
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 665-669 
    ISSN: 0009-2940
    Keywords: Semideltic acid ; Cyclopropenylium cations ; Pseudooxocarbon anions ; Semideltate anions ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Pseudooxocarbon Anions of Semideltic AcidNovel pseudooxocarbon anions of semideltic acid (2) can easily be obtained by stepwise substitution of the dimethylamino groups of the cyclopropenium perchlorate 8. Treatment of 8 with cyanamide or malononitrile in the presence of triethylamine leads to the triafulvenes 9 and 13. Two cyanoimino groups are successfully introduced into the cyclopropenylium system by treating 9 with excess cyanamide/potassium ethoxide. Under the same conditions malononitrile reacts with 13 to yield the potassium salts 14 and 17. The thioamide 26 of semideltic acid is obtained by treating the triphenylphosphonium salt 24 with H2S/pyridine and subsequent hydrolysis of the intermediate 25. With the anions of cyanamide or malononitrile ring-opening reaction of the cyclopropenylium system of 24 occurs to yield the push-pull phosphonium salts 28 and 29.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 60
    ISSN: 0009-2940
    Keywords: Ethylene-bridged metal complexes ; Ethanediyl complexes ; Manganese, Rhenium, Ruthenium, Osmium carbonyls ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Hydrocarbon-Bridged Metal complexes, XVIII. - Heterometallic Ethylene-Bridged Complexes (OC)5ReCH2CH2Mn(CO)5, (OC)5ReCH2CH2Ru(CO)2Cp, (OC)5ReCH2CH2Os(CO)4CH2CH2Re(CO)5 and (OC)5ReCH2CH2CH2Os(CO)4Os(CO)4(CO)4Os(CO)4CH2CH2Re(CO)5Addition of [(OC)5Re(C2H4)]+ to the carbonylmetallates [Mn(CO)5]-, [RuCp(CO)2]-, [Os(CO)4]2-, [Os3(CO)12]2- affords the title complexes in a directed way. The dynamic behaviour of (OC)5ReCH2CH2Mn(CO)5 in solution is attributed to a dyotropic exchange of the pentacarbonylmetal groups on the CH2CH2 bridge.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 61
    ISSN: 0009-2940
    Keywords: [2.2.2]Paracyclophane ligand ; (η6)π Complexes ; Arsenic(III) complexes ; Antimony(III) complexes ; Bismuth(III) complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Arsenic(III), Antimony(III), and Bismuth(III) Trihalide Complexes of [2.2.2]Paracyclophane: From Weak van der Waals Coordination to Strongly Directional π Complexation with Single or Double External η6 Coordination[2.2.2]Paracyclophane forms the adducts C24H24·AsCl3 (1), C24H24·(SbCl3)2·1/2 C6H6 (2), and C24H24·(BiCl3)3·C6H6 (3). For solutions in polar solvents NMR spectra indicate extensive dissociation and/or fluxionality. In the crystals adduct 1 features a weak addition of the AsCl3 molecule to one open side of a paracyclophane molecule with long intermolecular contacts approaching C3v symmetry. - Crystalline 2 shows SbCl3 coordination to two of the benzene rings of the hydrocarbon in a quasi-centered η6 mode, while one of the benzene rings remains uncoordinated. Chlorine-bridging between antimony atoms leads to tetrameric units (SbCI3)4 in the lattice. - In the bismuth compound 3 each benzene ring of the hydrocarbon is engaged in centroid (η6)π complexation, with the BiCl3 units crosslinked by chlorine bridges. The average of the Bi-ring distances (3.08,2.98, and 2.99 Å) is shorter than for the Sb-ring distances in 2 (3.047 and 3.050 Å), indicating stronger bonding. The crystal benzene is not coordinating.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 62
    ISSN: 0009-2940
    Keywords: Metallacyclic organoaluminium, -gallium and -indium compounds ; MOVPE precursors ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Intramolecularly base-stabilized four-coordinated metallacyclic organoaluminium, -gallium, and -indium compounds C5H10-Al(CH2)3NMe2 (4), C4H8Ga(CH2)3NMe2 (5), C5H10Ga(CH2)3N-Me2 (6), C5H10GaCH2CH(Me)CH2NMe2 (7), C4H8Ga(CH2)4NMe2 (8), C5H10Ga(CH2)4NMe2 (9), EtAl[(CH2)3]2NMe (10), MeGa-[(CH2)3]2NMe (11), EtGa[(CH2)3]2NMe (12), MeIn[(CH2)3]2NMe (13), and (14) have been synthesized by the reaction of [3-(dimethylamino)propyl]aluminium dichloride (1), [3-(dimethylamino)propyl]gallium dichloride (2), [3-(dimethylamino)-2-methylpropyl]gallium dichloride (3), or [4-(dimethylamino)butyl)gallium dichloride with the respective bis-Grignard reagents or by the reaction of the organometal dichlorides RMCl2 with bis[3-(chloromagnesio)propyl]methylamine or with N,N′-bis[3-(chloromagnesio)propyl]-N,N′-dimethyl ethylenediamine. Aluminium or gallium trichloride reacts with tris[3-(chloromagnesio)propyl]amine to give Al[(CH2)3]3N (15) and Ga[(CH2)3]3N (16). The 1H-, 13C-NMR and mass spectra of the new compounds as well as the X-ray crystal structure of 16 are discussed. 4, 6, and 12 have been tested successfully as MOVPE precursors.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 63
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1143-1148 
    ISSN: 0009-2940
    Keywords: Ironcarbonyl complexes ; ortho-Metallation ; o-Semidine rearrangement ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Iron Carbonyl Induced o-Semidine Rearrangement of 1-Alkyl-2-aryldiazenesIrradiation of pentacarbonyl iron in the presence of Me3C - N=N - Ar (Ar=phenyl, p-tolyl, p-CH3OC6H4) produces in the first step ortho-metallated complexes of the type Me3C - N - N(H)RC6H3Fe(CO)3Fe(CO)3 (2a-c, R=H, Me, MeO). In a thermal consecutive step these intermediates undergo an o-semidine rearrangement to Me3C - NFe(CO)3 - Fe(CO)3N(H)RC6H3 (1a-c). The structure of 1a has been elucidated by X-ray structure analysis. Dynamic 13C-NMR spectra indicate restricted rotation of the Me3C group and hindered carbonyl scrambling for the latter and former complexes, respectively.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 64
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1161-1162 
    ISSN: 0009-2940
    Keywords: Semiconductor ; Photocatalysis ; Carbon dioxide ; Formate ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Carbon dioxide is catalytically reduced to formate in a suspension of zinc sulfide in water/2,5-dihydrofuran when irradiated (λ ≥ 290 nm). Turnover rates are in the range of 1.5 monolayers CO2/h. No reaction occurs at pH=12, and a very slow one at pH=3.2,5-Dihydrofuran functions as reducing agent which is oxidized to dehydro dimers. When it is substituted by 2-propanol, no CO2 reduction is observed. Semiconductor photocatalysis by a two-electron transfer from zinc sulfide to adsorbed hydrogen carbonate is assumed as the key step of CO2 fixation.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 65
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1181-1186 
    ISSN: 0009-2940
    Keywords: Stereoselective cyclizations ; Ethers, cyclic ; Dipolar cycloaddition ; Nitro olefins ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A convenient conversion of aldehydes via nitroolefins 2 into cyclic ethers 6 fused to an isoxazoline ring involves formation of unsaturated nitroalkyl ethers 4 and subsequent intramolecular cycloaddition of an in situ-formed nitrile oxide olefin. The cyclization proceeds with stereoselective formation of trans over cis isomers in the tetrahydrofuran series and opposite stereoselectivity in the tetrahydropyran and hexahydrooxepine series, depending on the substituent R in the original nitro compound, thus providing access to stereoselectively functionalized cyclic ethers.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 66
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1223-1227 
    ISSN: 0009-2940
    Keywords: Cesium effect ; Clathrate ; Cyclophanes ; Acetylene, diphenyl ; Rigid-group principle ; Tolane ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Intra- and Extraannularly Functionalized [2.2.2]Phanes: Syntheses and PropertiesThe severely strained new cyclophanes 7b-f, consisting of bridged tolane subunits and bearing intraannular substituents R, were prepared mainly to study steric interactions of R with the “π cloud” of the triple bond. These compounds exist in a rigid twisted conformation, whereas the unsubstituted reference compound 7a and the extraannularly functionalized azo compound 9 show C2 symmetry. 9 forms a 1 : 1 clathrate with toluene.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 67
    ISSN: 0009-2940
    Keywords: Carbenoids ; Bromine-lithium exchange ; Asymmetric induction ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Bromine-lithium exchange in 1,1-dibromo-3-(trimethylsilyl-oxy)alkanes 4 and 6 affords the carbenoids 8 and 14, which have been added to ketones, aldehydes, arylboronates, and silylating agents. Diastereoselectivity in the generation and trapping of the carbenoids ranged between 70 - 90% for 8 and 〉90% for 14.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 68
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1271-1289 
    ISSN: 0009-2940
    Keywords: Dibenzo compounds, rigid face-to-face ; Photocycloadditions, [6 + 6] Benzo, Benzo ; Pagodanes, 4,9,14,19-tetrafunctionalized ; Functional Group Manipulations ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Various 4,9,14,19-tetrafunctionalized pagodanes are prepared by a de novo route commencing from appropriately substituted isodrin analogues (3, 4). With the 14,19-dimethoxypagodane-4,9-dicarboxylic esters 30/31, isolated after 16 one-pot operations (ca. 40 functional changes) in ca. 6.5% overall yield (ca. 84% per operation, ca. 93% per functional change), the scope for further functional group manipulations on the pagodane sphere is explored (e.g. diketone dicarboxylic ester 35, dimethoxy diketone 37, tetraketone 41). In two face-to-face dibenzo substrates (17, 49), clean photoequilibration with the corresponding syn-o,o'-dibenzo isomers (19, 50) (75: 25 and 80: 20, resp.) is observed upon direct excitation (λ=254 nm).
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 69
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1311-1312 
    ISSN: 0009-2940
    Keywords: Anthracene adducts ; Sulfine, chloro(trichloromethyl)- ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of Chloro(trichloromethyl)sulfine, Cl3C(Cl)C=SOThe unstable trichlorothioacetyl chloride (2) could be trapped by a Diels-Alder reaction with anthracene to form the adduct 3, which in turn could be oxidized to the corresponding sulfine adduct 4. Finnaly, chloro(trichloromethyl)sulfine (5) was prepared in good yield by vacuum thermolysis (retro Diels-Alder reaction) of 4.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 70
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1207-1213 
    ISSN: 0009-2940
    Keywords: Diazirines ; Phosphaalkynes ; Carbenes ; Phosphirenes ; [2 + 1] Cycloaddition ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Organophosphorus Compounds, 48. - 1-Halogen-1H-phosphirenes from Phosphaalkynes and ChlorocarbenesHalogen-substituted carbenes (7a - i), generated by thermolysis of diazirines (11a-i), add onto phosphaalkynes (8a-c) to form the title compounds (10a-1). Initially formed 2H-phosphirenes (9) could not be detected as their subsequent conversion to the 1H-isomers 10 by a 1,3-halogen shift is very fast. Hydrolysis of 10c,e,g-i and k yields vinylphosphonous acids (17a - e). 1-Chloro-1H-phosphirenes are transformed by nucleophilic substitution into fluoro (10a,c,e → 19a-c), bromo (10c,e → 20a,b), and iodo analogs (10c,e → 21a,b) with the help of silver tetrafluoroborate, trimethylsilyl bromide, and trimethylsilyl iodide, respectively. A crystal structure analysis of 10c is reported.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 71
    ISSN: 0009-2940
    Keywords: Carbene complexes of chromium and tungsten ; 1-Metalla-1,3,5-trienes ; 1-Metalla-1,3-dien-5-ynes ; Insertion of alkynes into M=C and C=C bonds ; [2 + 2] Cycloaddition reactions of carbene complexes and alkynes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Organic Syntheses via Transition Metal Complexes, 51. - 1-Metalla-1,3,5-trienes and 1-Metalla-1,3-dien-5-ynes of Chromium and Tungsten by Insertion of Alkynes into M=C and C=C Bonds of 1-Metalla-1,3-dienes and 1-Metalla-1-en-3-ynes, respectively1-Metalla-1,3,5-trienes LnM=C(NEt2)-C(Me)—C(OEt)-CH=CHPh (3,4) and LnM=C(OEt)- CH=C(NEt2) - C(Me)=CHPh [5, LnM=Cr(CO)5 (a), W(CO)5 (b)] are obtained for the first time from the corresponding 1-metalla-1,3-dienes LnM=C(OEt) - CH=CHPh (1a, b) under very mild conditions by the insertion of the electron-rich alkyne Et2N-C ≡ C - Me (2) into the M=C and the C=C bonds, respectively, of 1. The chelate complex (6b) and the cyclobutenyl carbene complex 7b are isolated as minor side products. 1-Metalla-1,3-dien-5-ynes LnM=C(NEt2) - C(Me)=C(OEt) - C ≡ CPh [9, 10, LnM=Cr(CO)5 (a), W(CO)5 (b)] are formed with high regio- and stereoselectivity on insertion of 2 into the M=C bonds of 1-metalla-1-en-3-ynes 8. X-ray data are given for the tungsten complex 3b.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 72
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1265-1270 
    ISSN: 0009-2940
    Keywords: Gas-phase pyrolysis ; Tandem mass spectrometry ; Carbonates ; Alkyl migration ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Gas-phase pyrolysis of dimethyl carbonate and its mono-, di-, and trithio analogs has been performed in the temperature range from 1253 to 1404 K applying the gas phase Curie-point pyrolysis technique. Real-time analyses have been carried out by means of mass-spectrometric techniques. The possible isomerizations of the ester functions have been studied by collisional activation mass spectrometry in combination with appropriate D, 18O, and 34S labeling. It is demonstrated that methyl group migrations can be induced pyrolytically in cases where oxygen-to-oxygen or oxygen-to-sulfur isomerizations are involved; in contrast, sulfur-to-oxygen as well as sulfur-to-sulfur isomerizations apparently do not take place.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 73
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991) 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 74
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1379-1395 
    ISSN: 0009-2940
    Keywords: Vinyl anions, chiral ; Umpolung ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The vinyllithium reagent 13 and its enantiomer are generated by a bromine/lithium exchange reaction starting from dibromoalkenes 11 and 12, both available from the corresponding enantiomer of alkyl lactate. When 13 is allowed to react with aldehydes or with acetophenone, a highly stereoselective addition to the Re face of the carbonyl compounds occurs to give predominantly the diastereomers 15. Alkenes 25a,c, accessible by another bromine/lithium exchange reaction of 15a,d and subsequent protonation, can be cleaved by ozonolysis followed by reduction to afford carbinols 27a, b in 〉 98% ee. The sequence corresponds to a stereoselective introduction of a methanol d1 synthon (⊖CH2OH) or, as shown by other examples, of acyl and formyl d1 synthons (⊖CRO and ⊕CHO) into prochiral carbonyl compounds. As a consequence, 13 and its enantiomer may be regarded as highly stereoselective reagents for "carbonyl umpolung". A series of further vinyllithium reagents, 38a-g and 54/55, is treated with benzaldehyde, but none of those displays comparable enantiofacial selectivity. The prerequisites to the highly stereoselective reactions of 13 and its enantiomer are briefly discussed.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 75
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1411-1414 
    ISSN: 0009-2940
    Keywords: Propane-1,2,3-trione, 1,3-diphenyl- ; Electron diffraction ; Gas-crystal structure comparison ; Conformation ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The molecular structure of 1,3-diphenylpropane-1,2,3-trione (diphenyl triketone) has been determined by gas-phase electron diffraction at 130°C nozzle temperature. It has been found that the phenyl rings are nearly coplanar with the adjacent carbonyl groups, and the two Cph-C(O)-C(O)-C(O) dihedral angles are - 129.5 ± 0.8 and - 107.1 ± 0.8° (0° corresponds to the syn form). Bond distances (rg, Å) and bond angles (deg) with estimated total errors are C—H 1.105 ± 0.006, O = C 1.213 ± 0.003, 〈 Cph-Cph〉 1.404± 0.003, Cph-C(O) 1.478 ± 0.005, C(O)-C(O) 1.558 ± 0.004, Cph-C(O)-C(O) 120.0 ± 0.3, Cph—C(O)=O 120.8 ± 0.4, C(O)-C(O)-C(O) 117.3 ± 0.4, Cph-Cph(CO)-Cph 119.8 ± 0.6. Although there is a general agreement between the gas-phase and crystal molecular structures there are some notable differences. One of the benzene rings is slightly turned about the Cph-C(O) axis in the opposite direction in the gas molecule as compared to the crystal. This causes a marked shortening of the O… H intramolecular contact (to 2.18 Á) between the central oxygen and an ortho-hydrogen.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 76
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1431-1434 
    ISSN: 0009-2940
    Keywords: Proton transfer ; Fragmentation of rings ; Aryllithium ; Carbanions ; Imines ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The title carbanions 1 are shown to lose nitrogen to afford ortho-carbiminophenyl anions 4 which can be protonated by inter- or intramolecular proton transfer or react inter- or intramolecularly with other types of electrophilic center.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 77
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1453-1460 
    ISSN: 0009-2940
    Keywords: Shock tube technique ; Oxygen scavanger ; Heat of formation ; Allyl resonance energy ; Radical disproportionation ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Heat of Formation of the Allyl and Methallyl RadicalThe decomposition of 1,5-hexadiene (1), 2-methyl-1,5-hexadiene (7), and 2,5-dimethyl-1,5-hexadiene (5) into allyl- (2) and methallyl radicals (6) was studied by means of the shoke tube technique with and without oxygen as scavanger. From these data and from the temperature dependence of the equilibria 1 ⇌ 2 and 5 ⇌ 6, measured between 600 and 800°C, the heat of formation of the allyl (2) and methallyl radical (6) as well as the activation parameters for the recombination and disproportionation of these radicals have been deduced.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 78
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1461-1470 
    ISSN: 0009-2940
    Keywords: Allyl stabilisation energy ; Calculations, force field ; Rotational barrier, intrinsic ; Gas-phase kinetics ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Rotational Barriers of Vinyl-Substituted OlefinesFor the vinyl-substituted olefines 1 - 14 activation parameters for the geometrical isomerisation have been determined in the gas-phase. By comparison of these barriers with the corresponding ones of the isolated double bonds, each corrected by the contribution of the steric energy to the ground and transition state, a value of 13.5 ± 1.1 kcal mol-1 for the allyl stabilisation energy (ASE), defined as replacement of alkyl by vinyl, has been derived.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 79
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1471-1475 
    ISSN: 0009-2940
    Keywords: Polyacetylenes ; Cross conjugation ; Alkenes, tetraethynyl ; π-Systems, planar ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: New Planar π-Systems, II1). - On the Preparation and Structure of Tetrakis(phenylethynyl)etheneThe preparation of tetrakis(phenylethynyl)ethene (1 b) has been repeated. Among various routes to this highly unsaturated cross-conjugated π-system, the dimerization of bromide 2 via the carbene 3 is the most simple one. Full spectroscopic data for 1 b are reported for the first time, as is its X-ray structural analysis at - 95°C.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 80
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1485-1487 
    ISSN: 0009-2940
    Keywords: Thioketenes ; Flash-vacuum pyrolysis ; Diels-Alder reaction ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Flash-vacuum pyrolysis of 2,4-bis(dichloromethylene)-1,3-dithietane (1) at 820°C furnishes dichlorothioketene (2a) which may be trapped with cyclopentadiene (3) in a [4+2] cycloaddition. The constitution 4a of the product is confirmed by an X-ray structural analysis of the related cycloadduct 4b.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 81
    ISSN: 0009-2940
    Keywords: Spirosilicates, zwitterionic ; Bond cleavage, Si - C ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Bis[2,3-naphthalenediolato(2 - )](pyrrolidiniomethyl)silicate Acetonitrile Solvate: Synthesis and Crystal and Molecular Structure of a Zwitterionic λ5-SpirosilicateThe zwitterionic spirocyclic bis[2,3-naphthalenediolato[2-)](pyrrolidiniomethyl)silicate (3) was synthesized and the crystal and molecular structure of its acetonitrile solvate 3 · CH3CN investigated. 3 was prepared by reaction of trimethoxy(pyrrolidinomethyl)silane (8) or dimethoxy(methyl)(pyrrolidinomethyl)silane (8) or dimethoxy(methyl)(pyrrolidinomethyl)silane (9) with 2,3-dihydroxynaphthalene in acetonitrile. Reaction 9 → 3 involves a remarkable Si - C cleavage with formation of CH4. The pentacoordinate silicon atom of 3 · CH3CN is surrounded by 4 oxygen atoms and 1 carbon atom, the latter being in an equatorial position. The coordination polyhedron can be described as a distorted trigonal bipyramid (the structure is displaced by 20.5% from the trigonal bipyramid towards the square pyramid). The crystal lattice of 3·CH3CN contains centrosymmetric dimers of 3, built up by intermolecular N - H … O hydrogen bonds.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 82
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1517-1520 
    ISSN: 0009-2940
    Keywords: Diiminosuccinonitrile ; 2H-Imidazoles ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Chemistry of Cyanogen: Reactions of Diiminosuccinonitrile (DISN) with Sulfenyl Chlorides, Chlorotrimethylsilane and Ring Closure to Trifluoromethyl-Substituted 2H-Imidazoles4,5-Dicyano-2-hydroxy-2-(trifluoromethyl)-2H-imidazole (1) is easily prepared by treating DISN with trifluoroacetic anhydride. In the presence of 4-(dimethylamino)pyridine, however, the O-acylated derivative 2 is formed in excellent yield, while the reaction of 1 with chlorotrimethylsilane affords the O-silylated product 6. A bi-1,2,5-thiadiazole of the formula S2(CN)4Cl2 (5) is the final reaction product, when DISN is treated with sulfur dichloride in the presence of “naked” chloride ions. On the other hand the non-heterocyclic N-sulfenyl derivative 4 has readily been obtained, when DISN is treated with F3CSCl instead. Finally a procedure is described to convert DISN into the corresponding N-silylated diimine 3.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 83
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1575-1577 
    ISSN: 0009-2940
    Keywords: Oxidative coupling of cyclopentadienide anion ; Dihydrofulvalene, molecular structure ; Migration of trimethylsilyl group ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reaction of 1,2,4-tris(trimethylsilyl)cyclopentadienyllithium with ferric chloride in THF at -95°C leads to the formation of a thermally sensitive iron(III) complex which decomposes to the new dihydrofulvalene derivative 3,7-dihydro-1,3,3,5,7,7-hexakis(trimethylsilyl)fulvalene (1).
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 84
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1677-1678 
    ISSN: 0009-2940
    Keywords: Cyclopentadienes, chiral ; Quinone adducts ; Diels-Alder reactions ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Diels-Alder adduct obtained by addition of quinone to the chiral cyclopentadiene 2 undergoes regioselective and stereoselective reduction after hydrogenation. The 4-hydroxy ketone 3 thus formed yields the title compound 1 in a thermal retro Diels-Alder process.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 85
    ISSN: 0009-2940
    Keywords: P - P bond ; Alkyne insertion ; Diphosphamolybdacyclopentene ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Metal-Containing Heterocycles: Preparation, Properties, Reactions, LXXV1).  -  Synthesis of a Diphosphamolybdacyclopentene by Alkyne Insertion into the P - P Bond of a DiphosphamolybdacyclopropaneInsertion of the alkyne RC≡CR (R = CO2Me) into the P - P bond of the diphosphamolybdacyclopropane (5-C5H5)-(OC)2Mo-PPh2-PAr (2) [Ar = 2,4,6-(tBu)3C6H2] results in the formation of the thermally and kinetically stable diphosphamolybdacyclopentene (η5-C5H5)(OC)2Mo-PPh2-RC = CR-PAr (3), which is characterized on the basis of mass, IR, 31P{1H}-, 1H-, and 13C{1H}-NMR spectra.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 86
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1733-1738 
    ISSN: 0009-2940
    Keywords: Phthalocyanine ; Ruthenium complexes ; Pyridines ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Soluble Bisaxially Substituted (Phthalocyaninato)ruthenium ComplexesSeveral attempts to prepare (tBu4Pc)Ru only led to an impure product (tBu4Pc)RuLx. This reacts quantitatively with pyridine to form (tBu4Pc)Ru(py)2, easily purified by chromatography. In addition the preparation of (tBu4Pc)RuL2 with L = pyridine, 2-picoline (2-pic), 3-picoline (3-pic), 4-picoline (4-pic), 2,5-lutidine (2,5-lut), and 2,6-lutidine (2,6-lut), respectively, is described. All complexes are characterized by spectroscopic methods including 1H-NMR spectroscopy. Not even in the cases of (tBu4Pc)RuL2 with L = 2-pic and 2,5-lut, a careful removal of the ligands L by thermogravimetric methods (TG/DTA) leads to pure (tBu4Pc)Ru. For comparison, the bisadducts PcRuL2 with L = pyridine, picolines (2-pic, 3-pic, 4-pic), lutidines (2,3-lut, 2,5-lut, 2,6-lut), and chloropyridines (2-Clpy and 3-Clpy), respectively, are prepared by treatment of PcRu with an excess of the ligand. For the first time (phthalocyaninato)iron complexes PcFeL2 with sterically hindered axial ligands, e.g. PcFe(2-pic)2, are prepared and characterized by 57Fe Mößbauer spectroscopy.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 87
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1809-1817 
    ISSN: 0009-2940
    Keywords: Lithiation ; Mannich reaction ; Alkylation ; Grignard reaction ; Condensation ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Phenols and naphthols are benzotriazolylmethylated by 1-(hydroxymethyl)-1H-benzotriazole (13) (a formaldehyde derivative) in the o- or (if both o-positions are occupied) in the p-position. The reaction can be extended to other aldehydes in the case of the naphthols. The methylene group in the o-(benzotriazolylmethyl)phenols can be lithiated (but only after trimethylsilyl protection of the hydroxy group) and then substituted by various electrophiles. The benzotriazole residues in both the primary products and in their substituted derivatives can be displaced by the alkyl anions of Grignard reagents or by hydride ions allowing the elaboration of many new types of substituted phenols.
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 88
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1827-1830 
    ISSN: 0009-2940
    Keywords: Cyclopropannelation ; Bicyclo[3.3.0]octane derivatives ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: To facilitate the synthesis of tetracycles containing the framework 2, the reaction of the tetrabromide 8 with cyanide and bis(phenylsulfonyl)methane under various conditions was investigated. Instead of the expected twofold bridging, novel cyclopropa derivatives were obtained. Product formation is a consequence of the stereochemistry of the starting material 8, with the exo configuration of the bromomethyl substituents being the crucial factor.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 89
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1837-1843 
    ISSN: 0009-2940
    Keywords: β-Hydroxycarboxylic acids, α-alkylation of ; EPC synthesis ; 1,3-Dioxan-4-ones, enolates of ; Enolates, naked ; Schwesinger's base ; Phosphazene P4 base ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Enolates A of the dioxanones specified in the title, when generated with lithium amide bases, can only be alkylated with highly reactive electrophiles, and only once. With Schwesinger's t-Bu-P 4 base (a very strong, so-called neutral base, containing 4P and 13N atoms capable of bearing a positive charge in the conjugate P4H+ cation) the dioxanone 1 can be doubly alkylated even with iodobutane (products 16, 17). The 5,6-dimethyl- and 5-benzyl-6-methyldioxanone 2 and 3 can be alkylated diastereoselectively with the formation of quaternary centers at C(5) (products 4, 8 - 14). In one case, the configuration of the product 4 obtained was determined by conversion to a β-lactone 6 and an olefin 7 (a previous assignment had to be revised). Even the 2,5,6,6-tetraalkyl-substituted dioxanone 19 could be further alkylated (→ 20 + 21). Five of the new alkylation products were hydrolyzed to the parent 3-hydroxy-carboxylic acids 5, 22  -  25. The enormous reactivities achieved with the inherently labile enolates and the P411+ counterions are discussed.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 90
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1845-1852 
    ISSN: 0009-2940
    Keywords: (R)-3-Hydroxybutyric acid ; Aldol addition, regioselective, steric course of ; 1,3-Dioxin-4-ones, lithium dienolates of ; EPC synthesis ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reactions of Dienolates from (R)-2-tert-Butyl-6-methyl-4H-1,3-dioxin-4-one with Aldehydes and Ketones  -  a Chiral Acetoacetic Ester d4-Reagent
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 91
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1853-1863 
    ISSN: 0009-2940
    Keywords: Carbenes ; Oxygen ylides ; Stevens rearrangement ; Oxonium ions ; Insertion, O - H ; Ylides ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reactions of Carbenes with Oxetane and with Oxetane/Methanol MixturesEthoxycarbonylcarbene, bis(methoxycarbonyl)carbene, phenylcarbene (17a), diphenylcarbene (17b), fluorenylidene (17c), 2-furylcarbene (31a), 2-furyl(phenyl)carbene (31b), 4-oxo-2,5-cyclohexadienylidene (40), and 4,4-dimethyl-2,5-cyclohexadienylidene (53) were generated by photolysis of the appropriate diazo compounds. With neat oxetane, most of these carbenes react by competitive C - H insertion (B → A, Scheme 1) and ylide formation (B → C). 31a and 40 do not insert into C - H bonds; 31b does not attack oxetane but rearranges exclusively with formation of 26. The ylides undergo Stevens rearrangement to give tetrahydrofurans (C → D) and α´,β-elimination, leading to allyl ethers (C → E). With oxetane/methanol mixtures, the intervention of oxonium ions (H) is indicated by the formation of 1,3-dialkoxypropanes (I). The oxonium ions arise either by protonation of the ylides (C → H) or by protonation of the carbenes (B → G), followed by electrophilic attack of the carbocations (G) at oxetane (G → H). The former route is followed by the alkoxycarbonylcarbenes and by 40; the ylides derived from the remaining carbenes do not react with methanol, owing to their rapid Stevens rearrangements. Protonation of the carbenes 17b, 31, and 53 is clearly indicated by their product ratios and, for 31, by the formation of isomeric ethers (33, 36). The more electrophilic carbenes discriminate but slightly between oxetane and methanol while the more nucleophilic carbenes (17b, 31,53) prefer the protic methanol strongly over the aprotic oxetane.
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 92
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1871-1874 
    ISSN: 0009-2940
    Keywords: Conjugate addition ; Cuprates ; 1,3-Dienes ; Wittig reaction ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 93
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1879-1880 
    ISSN: 0009-2940
    Keywords: Fluoromethanesulfonyl chloride ; Potassium fluoride ; Crown ether ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Introduction of fluorine into 4-chlorobenzyl chloromethyl sulfide (7) by crown-ether-assisted nucleophilic substitution furnishes 4-chlorobenzyl fluoromethyl sulfide (5), a key intermediate for the preparation of fluoromethanesulfonyl chloride (1).
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 94
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1881-1884 
    ISSN: 0009-2940
    Keywords: Dioxastannolane ; Carbon disulfide ; Isothiocyanate ; Cycloaddition, stereospecific ; Lewis base ; 1,3-Dioxolane-2-thione ; 1,3-Dioxolan-2-imine ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1,3-Dioxa-2-stannolanes 1 are readlily activated by Lewis bases such as Bu3P and Et3N to give cycloadducts on reaction with carbon disulfide or phenyl isothiocyanate under mild conditions. In particular, bases play a characteristic role in the reaction with carbon disulfide to produce 1,3-dioxolane-2-thiones 2 in good yields, while spiro compounds 3 (1:2 adducts) are predominantly obtained in the absence of bases.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 95
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1889-1893 
    ISSN: 0009-2940
    Keywords: Clusters ; Rhodium complexes ; Hydroformylation ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Large Transition Metal Clusters, VIII. - How Do Supported Rh55 Clusters Behave in the Hydroformylation Process?Two-shell rhodium clusters of the type Rh55L12Clx [L = P(tBu)3, x = 20; L = PPh3, x = 6] can be anchored on TiO2 and Na- Y-zeolite. High resolution transmission electron microscopy (HRTEM), BET, and DSC investigations prove that the clusters, about 20 Å in diameter, are fixed on the entrances of the micropores of the supports. The supported clusters catalyze the hydroformylation of ethene and propene variously. During the hydroformylation of ethene without a solvent or in aqueous suspension the catalyst is inactive after a few cycles. However, there is no loss of activity even after 27 experiments if propene is hydroformylated in an aqueous medium.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 96
    ISSN: 0009-2940
    Keywords: Selane, bis(sulfinylamido)- ; Diselane, trimethylsilyl- ; 1,3,4,2,5-Thiadiselenadiazolium ; 1,3,2,4-Thiaselenadiazete-Titanium tetrachloride ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis, Structures, and Properties of Cyclothiaselenazenium Cations [[Se2N2S]22+, [XSe2N2S]+, [Se2N2S]2+, [S3SeN5]+as well as Cl2Se2N2S and SeSN2 and SeSN2 ṁ TiCl4Bis(sulfinylamino)selane (1), prepared from Se2Cl2 and (CH3)3SiNSO, reacts with Lewis acids such as MF5 (M = As, Sb, Nb) and BF3 to form bis(1,3,4,2,5-thiadiselenadiazolium) cations (3) with counter anions AsF-6 (3a), SbF-6 (3b), NbF-6 (3c), BF-4 (3d). Treatment of Se2Cl2 with LiN[Si(CH3)3]2 leads to [(CH3)3Si]2NSexN[Si(CH3)3]2 (x = 1, 2a: 2, 2b). From 2a and 2a and SeCl4 explosive Se4N4 is obtained. Chlorination of 3a and 3c gives [ClSe2N2S]+[MF6]- (M = As, 4a, and Nb, 4c). Analogous bromination of 3a provides [BrSe2N2S]+ [AsF6]- (4b). This type of chlorinated five-membered rings is also obtained directly from 1 and SbCl5 and PCl5 or SeCl4. The products isolated are [ClSe2N2S]+ [SbCl6]- (4d) and [ClSe2N2S]+Cl- (4e). - A covalent species 5, isomeric to 4e, is obtained from 1 and POCl3, and a four-membered ring SeSN2 ṁ TiCl4 (6) from 1 and TiCl4. When 3a or 1 is treated with a two- or threefold excess of AsF5 the stable dication [Se2N2S]2+ (7) is formed. It arises also from 4e and AgAsF6. Attempts to replace TiCl4 in 6 by AsF5 lead to [SeS3N5]+ [AsF6]- (8) with a bicyclic structure for the cation. X-ray structure analyses for 1, 4c, 4d, 4e, 5, and 8 are performed.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 97
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1941-1945 
    ISSN: 0009-2940
    Keywords: Lithium (di-tert-butylfluorosilyl)amide ; Cyclotetrasilazane ; 1,3,5-Triamino-2,4,6-trisilazane ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Aminodi-tert-butylfluorosilane (CMe3)2 SiFNH2 reacts with BuLi in hexane to give the lithium derivative 1, which crystallizes from TMEDA with formation of the dimer 2 [(CMe3)2SiFNHLi(TMEDA)]2. LiF elimination from 1 or 2 leads to cyclodi- (3), -tri- (4), and -tetrasilazane (6). 3 is the main product of the LiF elimination from 2 and 4 the main product resulting from 1. Cyclotetrasilazane 6 is the most planar eightmembered Si-N ring known so far. Chain compound 5 is the direct precursor of 4. The crystal structures of 2, 5, and 6 are described.From the Lithium Derivative of Amino-di-tert-butylfluorosilane to Cyclodi-, -tri-, and -tetrasilazanes
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 98
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1953-1956 
    ISSN: 0009-2940
    Keywords: Trisilylmethane ; 1,1,1-Trisilylethane ; CVD feedstock gases ; Silicon carbide, hydrogenated, amorphous (a-SiC:H) ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: As a precursor for trisilylmethane, tris(phenylsilyl)methane is prepared by a Merker-Scott reaction of chlorophenylsilane, bromoform, and magnesium turnings in boiling tetrahydrofuran. Chlorophenylsilane is formed in a new synthesis starting from phenylsilane and hydrogen choride/AlCl3 in diethyl ether. The gas phase structure of trisilylmethane (H3Si)3CH, obtained from (PhSiH2)3CH via (BrSiH2)3CH, has been determined by electron diffraction. Data refinement confirmed a model of C3 molecular symmetry, with local C3v symmetry for the silyl groups.  -  As a precursor for 1,1,1-trisilylethane, 1,1,1-tris(phenylsilyl)ethane has been prepared similarly from chlorophenylsilane, 1,1,1-trichloroethane and magnesium and converted via 1,1,1-tris(bromosilyl)ethane into CH3C(SiH3)3.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 99
    ISSN: 0009-2940
    Keywords: Imido ligands ; Molybdenum complexes ; Tungsten complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Organometallic Imido Complexes - Higher Valent Derivatives of the d-Metal Acids, 1. - New Organometallic Imido Complexes of Molybdenum and Tungsten - Direct Introduction of the Cyclopentadienyl Group by Masking the High-Oxidation StateThe molybdenum(VI)bis(tert-butylimido) complex MO(NtBu)2-Cl2 is converted into the novel organomolybdenum(VI) derivative (η5-C5H5)MO(NtBu)2Cl (1) in excellent yield. The preparation of the pyridine complex W(NtBu)2Cl2py2 (2) provides a convenient starting material for an effective synthesis of the related complex (η5-C5H5)W(NtBu)2Cl (4).
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 100
    ISSN: 0009-2940
    Keywords: π-Acceptor ; Charge-transfer complex ; 1,4-Benzoquinone diimine, N,N′-dicyan, 2,5-dimethyl- ; Tetrathiafulvalene ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Multi-Step Redox Systems, LV. - Crystal Structure of the CT Complex 2,5-Me2-DCNQI/TTF from N,N′-Dicyano-2,5-dimethyl-1,4-benzoquinone Diimine and Tetrathiafulvalene and of the Acceptor 2,5-Me2-DCNQIThe crystal structure of the title compound is described and discussed in terms of a neutral non-conducting mixed-stack CT complex. X-ray data for the acceptor 2,5-Me2-DCNQI are given for comparison.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...