Browsing by Author "Tangen, Espen"
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Tangen, Espen (Doctoral thesis; Doktorgradsavhandling, 14-Oct-2008)[+][-]
Abstract: To contribute to the fundamental picture of the electronic structure of low-coordinate transition metal complexes, we have carried out a series of DFT studies on mono-imido and nitrosyl complexes for different metal ions (MnII/III, FeII/III/IV, CoII/III) and different systems of basal ligands. These studies reveal striking similarities of the electronic structure for these systems. The distinction of bent versus linear NO units is attributed to the ranking of the dz2 and dxz/yz parentage MOs relative to each other. Without a ligand trans to the NO group, the antibonding metal dz2- NO σ orbital interaction is lessened by mixing in metal pz, causing the MO to shift away from the NO ligand. This exact same orbital interaction appears to explain the existence of middle to late first-row transition metal imido complexes. Description: The four papers of the thesis are not available in Munin, due to publishers' restrictions:
1. Tangen, E.; Svadberg, A.; Ghosh, A. "Toward Modeling H-NOX Domains: A DFT Study of Heme-NO Complexes as Hydrogen Bond Acceptors," Inorganic Chemistry 2005, 44, 7802-7805. (American Chemical Society) Available at http://dx.doi.org/10.1021/ic050486q
2. Tangen, E.; Conradie, J.; Ghosh, A. "The Challenge of Being Straight: Explaining the Linearity of a Low-Spin {FeNO}7 Unit in a Tropocoronand Complex," Inorganic Chemistry 2005, 44, 8699-8706. (American Chemical Society) Available at http://dx.doi.org/10.1021/ic050781a
3. Conradie, J.; Tangen, E.; Ghosh, A. "Trigonal bipyramidal iron(III) and manganese(III) oxo, sulfido, and selenido complexes. An electronic-structural overview," Journal of Inorganic Biochemistry 2006, 100, 707-715. (Elsevier Science) Available at http://dx.doi.org/10.1016/j.jinorgbio.2006.01.029
4. Tangen, E.; Conradie, J.; Ghosh, A. "Bonding in Low-Coordinate Environments: Electronic Structure of Pseudotetrahedral Iron-Imido Complexes," J. Chem. Theory Comput. 2007, 3, 448-457. (American Chemical Society) Available at http://dx.doi.org/10.1021/ct600318nURI: http://hdl.handle.net/10037/1725 File(s) in this item: 1
thesis.pdf (3.713Mb) -
Tangen, Espen (Master thesis; Mastergradsoppgave, 06-Jun-2003)[+][-]
Abstract: To contribute to the fundamental picture of the electronic structure of high valent first row transition metal complexes, I have carried out a density functional study of two different macrocyclic ligand systems, corroles and corrolazines, with two different axial ligands, Ph and Cl and a number of different central ions, P(V), Cu(III), Mn(IV) and Fe(IV). DFT calculations on Fe(IV) and Mn(IV) corrole and corrolazine derivatives suggest that compared with the often noninnocent corrole ligands, corrolazines are electronically more innocent and stabilize “purer” high-valent states of transition metal ions. This study also contributes to the idea that (Cor)FeIVCl complexes are best regarded as intermediate spin (S=3/2) Fe(III) centers antiferromagnetically coupled to a corrole ð-type cation radical, making the corrole ligand noninnocent. The nature of this coupling seems to be an Fe(dz2)-corrole(b1) orbital interaction for (Cor)FeIVCl. For (Cor)FeIVPh, however, the situation seems to be different. Like in the Fe(IV) corrole µ-oxo dimers, the corrole ligand has less radical character. DFT(PW91/TZP) studies of (Cor)MPh (M = Fe, Mn, Co) suggests that also metal(dzx)-corrole(a2) orbital interactions may contribute to the ligand noninnocence in high valent metal corrole complexes. In other words, different high-valent metallocorroles may exhibit b1-type, a2-type or no radical character. URI: http://hdl.handle.net/10037/229 File(s) in this item: 1
thesis.pdf (2.424Mb)
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