title: [Co5Tp*4(Me2bta)6]: A Highly Symmetrical Pentanuclear Kuratowski Complex Featuring Tris(pyrazolyl)borate and Benzotriazolate Ligands.
abstract: The pentanuclear Co(II) complex [Co5Tp*4(Me2bta)6] containing N-donor ligands (5,6-dimethyl benzotriazolate; Me2bta6) and N-donor capping ligands (tris(3,5-dimethyl-1-pyrazolyl)borate; Tp*) was prepared by a simple and efficient ligand exchange reaction from [Co5Cl4(Me2bta)6] and tetra-n-butyl ammonium tris(3,5-dimethyl-1-pyrazolyl)borate. Compared to the precursor complex [Co5Cl4(Me2bta)6], which contains one Co(II) ion in octahedral and four Co(II) ions in tetrahedral coordination geometry, the title compound features all five Co(II) ions in an octahedral coordination environment while keeping a high complex symmetry. This results in modified properties including improved solubility and distinct magnetic behavior as compared to the precursor complex. The molecular structure and phase purity of the compound was verified by XRPD, UV-vis, ESI-MS, IR, and NMR measurements. Thermal stability of the compound was determined via TGA. The magnetic properties of here reported novel complex [Co5Tp*4(Me2bta)6] as well as its precursor [Co5Cl4(Me2bta)6] were examined in detail via ESR and SQUID measurements, which indicated weak anti-ferromagnetic exchange interactions between high-spin Co(II) centers at T < 20 and 50 K, respectively.
authors.affiliation: Chair of Solid State and Materials Chemistry, Institute of Physics, University of Augsburg , Universitaetsstrasse 1, D-86159 Augsburg, Germany.
authors.forename: Tamas W
authors.initials: TW
authors.lastname: Werner
authors.affiliation: Experimental Physics V, Center for Electronic Correlations and Magnetism, Institute of Physics, University of Augsburg , Universitaetsstrasse 1, D-86159 Augsburg, Germany.
authors.forename: Stephan
authors.initials: S
authors.lastname: Reschke
authors.affiliation: Chair of Solid State and Materials Chemistry, Institute of Physics, University of Augsburg , Universitaetsstrasse 1, D-86159 Augsburg, Germany.
authors.forename: Hana
authors.initials: H
authors.lastname: Bunzen
authors.affiliation: Experimental Physics V, Center for Electronic Correlations and Magnetism, Institute of Physics, University of Augsburg , Universitaetsstrasse 1, D-86159 Augsburg, Germany.
authors.forename: Hans-Albrecht Krug
authors.initials: HA
authors.lastname: von Nidda
authors.affiliation: Experimental Physics V, Center for Electronic Correlations and Magnetism, Institute of Physics, University of Augsburg , Universitaetsstrasse 1, D-86159 Augsburg, Germany.
authors.forename: Joachim
authors.initials: J
authors.lastname: Deisenhofer
authors.affiliation: Experimental Physics V, Center for Electronic Correlations and Magnetism, Institute of Physics, University of Augsburg , Universitaetsstrasse 1, D-86159 Augsburg, Germany.
authors.forename: Alois
authors.initials: A
authors.lastname: Loidl
authors.affiliation: Chair of Solid State and Materials Chemistry, Institute of Physics, University of Augsburg , Universitaetsstrasse 1, D-86159 Augsburg, Germany.
authors.forename: Dirk
authors.initials: D
authors.lastname: Volkmer