Marianne Sundbom

X-ray photoelectron and mössbauer spectroscopy on a variety of iron compounds

Abstract A combination of X-ray photoelectron spectroscopy (ESCA) and Mossbauer spectroscopy has been used to study the chemical shifts of a series of iron complexes. Obtained experimental data will constitute a basis for comparison with theoretical studies.

Interpretation of the 57Fe Isomer Shift by Means of Atomic Hartree–Fock Calculations on a Number of Ionic States

The Hartree–Fock method is used to calculate the values of |u2009Ψ(0)u2009|2 for a number of configurations of different Fe ions. An interpolation formula for |u2009Ψ(0)u2009|2 as a function of the occupation number of valence electron orbitals (3d, 4s, 4p) is given. Experimental Mossbauer isomer shifts are correlated to estimated configurations which are compared to available MO calculations for a few cases.

A theoretical investigation of the electronic structure and excited states of copper porphin

Abstract A semiempirical open shell SCF-MO method with zero differential overlap has been applied in an investigation of the electronic structure and excited states of copper porphin. The nature of the metal ligand bond is discussed. The “backbonding effect” is found to be negligible for the stability of the complex. An analysis of the different types of transitions found in the electronic spectrum is made. New bands ( d-d and CT) are predicted. ESR parameters have been calculated and show good agreement with experimental values. The conventional deduction of MO coefficients from ESR data is critically analysed.

A semiempirical MO study of the electronic structure and excited states of the Tris(2,2′-bipyridyl)Iron(II) and Tris(glyoxal-Bis-N-methylimine)iron(II)Ions

A semi-empirical SCF-MO method, the PEEL method, has been applied in an investigation of the electronic structure and excited states of two iron compounds, [Fe(II)-(GMI)3]++ and [Fe(II)-(bipy)3]++.The electronic absorption spectra have been recorded. The calculations show that it is necessary to account for the trigonal distortion and the covalency in order to explain these spectra quantitatively. Mössbauer measurements have also been performed. The calculated electronic population of the iron is in accord with Mössbauer isomer shift data, indicating that a realistic electron distribution has been obtained by the PEEL method.ZusammenfassungEine semiempirische SCF-MO-Methode, die PEEL-Methode, wurde zur Untersuchung der Elektronenstruktur sowie von angeregten Zuständen der beiden Eisenverbindungen [Fe(II)-(GMI)3]++ und [Fe(II)-(bipy)3]++ angewendet.Die elektronischen Absorptionsspektren wurden aufgenommen. Die Berechnungen zeigen, daß die trigonale Verzerrung und die Kovalenz berücksichtigt werden müssen, um die Spektren quantitativ zu erklären. Mössbauer-Messungen wurden ebenfalls durchgeführt. Die berechnete Elektronenverteilung am Eisenatom ist in Übereinstimmung mit den Daten der Isomerenverschiebung der Mössbauer-Messungen, wodurch gezeigt wird, daß mit der PEEL-Methode eine realistische Elektronen-Verteilung erhalten wurde.RésuméUne méthode SCF-MO semi-empirique, la méthode PEEL, a été appliquée à une étude de la structure électronique et des états excités de deux composés ferreux: [Fe(II)-(bipy)3]++ et [Fe(II)-(GMI)3]++. Les spectres dabsorption électronique ont été enregistrés. Les calculs montrent quil est nécessaire de rendre compte de la distorsion trigonale et de la covalence pour expliquer ces spectres quantitativement.Des mesures de leffet Mössbauer ont aussi été effectuées. La population électronique calculée du fer est en bon accord avec les données sur le déplacement isomérique de Mössbauer, ce qui indique que la méthode PEEL fournit une distribution électronique réaliste.

Theoretical studies of electrophilic substitutions in fluorobenzene

Abstract Results from an ab initio MO LCAO SCF study of the electronic structure of fluorobenzene are reported. A minimal basis set of contracted gaussian functions has been used to calculate the electrostatic molecular potential. The obtained isopotential maps indicate that fluorine has a para-directing effect in accordance with chemical evidence.

Use of the Mössbauer isomer shift and the X-ray emission Kα shift to estimate the effective electronic population of iron in complexes

Abstract The Hartree-Fock method is used to calculate the K α transition energy for a number of configurations of different Fe ions. Experimental X-ray emission K α shifts are combined with Mossbauer isomer shifts to estimate the effective configurations of the iron ion.