Die Berechnung von Einelektronen-Integralen in der SCF-Xα-SW-Methode: I. Die Normierung

A normalization of the wave functions by means of the theoretical exact Multiple-Scattering-(MS)-formalism is discussed within the framework of the SCF-X-SW-method. For the atomic and extramolecular regions the integrals of normalization can be easily determined and the results can be described by the corresponding electronic charges. The calculation of the integral of the interatomic region is problematic. The needful volume integration is only necessary to theGreen's functions of the wave functions and can be solved by means of the residual theory. The further analytical calculation of the surface integrals leads to a complicated formalism which can be numerically evaluated.

     

Eine vollst?ndige Trennung der Ammoniak- und Schwefelammoniumgruppe und der Phosphors?ure

Ohne Zusammenfassung     

Eichinvariante Berechnung des Diamagnetismus und der chemischen Verschiebung, 2. Mitt.: Berechnung magnetischer Daten von zweiatomigen Molekülen auf der Grundlage lokalisierter Orbitale

Expressions are derived for the decomposition of tensorial properties into additive increments.In the second part of the paper calculations of _H andC _H for LiH and of the susceptibilities for Li₂, BH, HF, CO, F₂, and LiF are presented. The contributions of the various LMO's to , ^P andg-values are discussed. The results are compared to those obtained from coupledHF-perturbation theory and to experimental values where available. The values for are in good agreement with the experiment and—except for BH—with theHF-perturbation theory, however deviations are found in some molecules for andg-values and traced back to specific electronic features.     

Zum Formalismus der LCPO-MO-Methode

Based on the combination ofPars-Orbitals (PO) the LCPO-MO-Method has been described for the quantum chemical treatment of large molecules which are divided in reasonable fragments. The secular matrix constructed from the Eigenvalues and parameters of the molecular fragments has a characteristic block-form. The dimension of the secularproblem can be reduced and depends on the used approximations. The resulting method is demonstrated for naphthalene.

Herrn Professor Dr.O. E. Polansky zu seinem 60. Geburtstag gewidmet.     

Das verhalten von mono- und diorganylphosphansulfiden gegenüber metallcarbonylsystemen: VII . Präprative,kinetische und spektroskopische untersuchungen über die isomerisierung verschiedener sekundärer phosphansulfide an carbonylsystemen von metallen der VI. nebengruppe

Cycloheptatrienemolybdenum tricarbonyl reacted with ligands (L) (L = phenyl-, o-tolyl-, m-tolyl-, p-tolyl-, α-naphthyl-, β-naphthyl-, sym-diphenyl-, sym-di-o-tolyl-, sym-di-p-tolyl, or sym-di-α-naphthyl-thiourea) to give Mo(CO)₅L derivatives although the expected products were cis-Mo(CO)₃L₃. Evidence has been obtained for the formation of trans-Mo(CO)₄L₂ derivatives when L = sym-diphenyl- and sym-di-o-tolyl-thiourea. These donors on reaction with Mo(CO)₄B (B = o-phenanthroline or 2,2′-bipyridine) yielded mixed ligand derivatives of the type Mo(CO)₃BL. The appearance of three CO stretching bands is in agreement with the C_s symmetry of mixed-ligand molybdenum carbonyls.     

Die Berechnung von Einelektronen-Integralen in der SCF-Xα-SW-Methode: II. Einelektronen-Eigenschaften

Based on the scattered-wave formalism the one-electron integrals have been investigated. It could be demonstrated that the integrals of the spheric-symmetrical regions can be determined conveniently. Caused by the complicated geometrical shape the contribution of the interatomic region to this integral was difficult to determine. A surface integral expression has been obtained as the solution which exact calculation will be very complicated and time consuming. Therefore a ZDO-analogous approximations are considered. By this means a formalism was derived which can be further reduced (simplified) and analysed relatively easily if a concrete operator is known.

     

Advances in Molecular Diamagnetism

At the present state of instrumentation and quantum-mechanical approximations, diamagnetic measurements can supply information on chemical structure which complements the result of other approaches, such as infrared and NMR spectroscopy. General applicability and relatively low cost of equipment are among the advantages of this technique. There is growing interest in the relation to chemical shifts in NMR spectra and in the possibility offered by this technique for testing quantum-chemical approximations.     

Eichinvariante Berechnung des Diamagnetismus und der chemischen Verschiebung

The procedure derived in^1–6 was used to calculate the magnetic susceptibilities and the magnetic shielding of a series of diamagnetic molecules (CH₄, C₂H₆, C₂H₄, C₂H₂, and HCN). The model requires only the knowledge of the unperturbed electron density. An incrementary treatment of the susceptibility-and shielding tensors is based on a partition of the electron density into localized parts.The values obtained by this procedure are in good agreement with experimental results in the case of susceptibilities and magnetic protonshieldings. The results for the¹³C-shielding however are not satisfactory.

     

Calculation of the susceptibility of aromatic compounds with a localized MO model

Using previously derived equations for the susceptibility [8] we calculated the components of the susceptibility tensor for ethene, benzene and naphthalene. Starting from PCILO bond orbitals and energy localized orbitals we evaluated theoretical increments for the susceptibility of the bonds building up these molecules. It was demonstrated that only with banana bonds was it possible to obtain satisfactory mean values and the right sign of the anisotropy, whereas a bond scheme with ∝ and π bonds yielded considerably worse values. The benzene value of X _m=?712·6×10^?12 m³ mol^?1 resulted from a Kekulé structure with three a bonds and three pairs of r bonds and the naphthalene value of X _m=?1137·4×10^?12 m³ mol^?1 from a similar bond scheme.