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Computational studies of dibenzotetraaza[14]annulene Ni(II) and Zn(II) complexes

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Title: Computational studies of dibenzotetraaza[14]annulene Ni(II) and Zn(II) complexes
Author(s): Pruikkonen, Sanni
Contributor: University of Helsinki, Faculty of Science
Degree program: Master's Programme in Theoretical and Computational Methods
Specialisation: no specialization
Language: English
Acceptance year: 2021
Abstract:
Stacking of antiaromatic molecules leads to enhanced stability and higher conductivity due to reversed antiarotmaticity. It has been shown that cyclophenes consisting of antiaromatic Ni(II) norrcorrole subunits have a vertical current-density flux between the two metal ions. The Ni(II) meso- substituted dibenzotetraaza[14]annulene complex fulfills the Hückel rule for being antiaromatic. Upon increasing the temperature above 13 K, the effective magnetic moment of solid state Ni(II) meso-substituted dibenzotetraaza[14]annulene changes from being diamagnet to paramagnetic. A suggested explanation for this is that there might be weak interaction between the Ni atoms. In this study the possibility of the existence of vertical current-density flux between the two metal ions in the Ni(II) meso-substituted dibenzotetraaza[14]annulene is investigated. In addition, the effect of the Ni and N atoms in Ni(II) 1,5,9,13-tetraaza[16]annulene was studied by replacing Ni and Zn and N with O. Electronic motion in molecules that are under the influence of a magnetic field is investigated computationally, since at present there is no routine experimental method for doing that. TURBOMOLE, the Gauge-including Magnetically Induced Currents method and Paraview were employed in this study for structure optimization of the molecules, calculation of current-density flux and current strength in the molecules and visualisation of the current-density pathways respectively. The results of this study does not show any current transport between the subunits in the Ni(II) meso-substituted dibenzotetraaza[14]annulene complex. Both the Ni(II) 1,5,9,13-tetraaza[16]annulene and the Zn(II) 1,5,9,13-tetraaza[16]annulene are aromatic but they were not stacked due to their distorted structure. The (2Z,7Z,10Z,14Z)-1,9-dioxa-5,13-diazacyclohexadeca-2,7,10,14-tetraene-5,13-diide complexes with either Zn(II) or Ni(II) were both non-aromatic as well as the Ni(II) (2Z,7Z,10Z,14Z)-1,9-dioxa-5,13-diazacyclohexadeca-2,7,10,14-tetraene-5,13-diide dimer.
Keyword(s): Ni(II) dibenzotetraaza[14]annulene 1 5 9 13-tetraaza[16]annulene Magnetically induced current densities GIMIC


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