Synthesis, magnetic properties, and STM spectroscopy of cobalt(II) Cubanes [Co(II) (4)(Cl)(4)(HL)(4)].

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Details zur Publikation

Autor(en): Scheurer A, Ako AM, Saalfrank R, Heinemann F, Hampel F, Petukhov K, Gieb K, Stocker M, Müller P
Zeitschrift: Chemistry - A European Journal
Jahr der Veröffentlichung: 2010
Band: 16
Heftnummer: 16
Seitenbereich: 4784-4792
ISSN: 0947-6539
eISSN: 1521-3765


Abstract

Reaction of cobalt(II) chloride hexahydrate with N-substituted diethanolamines H(2)L(2-4) (3) in the presence of LiH in anhydrous THF leads under anaerobic conditions to the formation of three isostructural tetranuclear cobalt(II) complexes [Co(II) (4)(Cl)(4)(HL(2-4))(4)] (4) with a [Co(4)(mu(3)-O)(4)](4+) cubane core. According to X-ray structural analyses, the complexes 4 a,c crystallize in the tetragonal space group I4(1)/a, whereas for complex 4 b the tetragonal space group P$ar 4$ was found. In the solid state the orientation of the cubane cores and the formation of a 3D framework were controlled by the ligand substituents of the cobalt(II) cubanes 4. This also allowed detailed magnetic investigations on single crystals. The analysis of the SQUID magnetic susceptibility data for 4 a gave intramolecular ferromagnetic couplings of the cobalt(II) ions (J(1) approximately 20.4 K, J(2) approximately 7.6 K), resulting in an S=6 ground-state multiplet. The anisotropy was found to be of the easy-axis type (D=-1.55 K) with a resulting anisotropy barrier of Delta approximately 55.8 K. Two-dimensional electron-gas (2DEG) Hall magnetization measurements revealed that complex 4 a is a single-molecule magnet and shows hysteretic magnetization characteristics with typical temperature and sweep-rate dependencies below a blocking temperature of about 4.4 K. The hysteresis loops collapse at zero field owing to fast quantum tunneling of the magnetization (QTM). The structural and electronic properties of cobalt(II) cubane 4 a, deposited on a highly oriented pyrolytic graphite (HOPG) surface, were investigated by means of STM and current imaging tunneling spectroscopy (CITS) at RT and standard atmospheric pressure. In CITS measurements the rather large contrast found at the expected locations of the metal centers of the molecules indicated the presence of a strongly localized LUMO.


FAU-Autoren / FAU-Herausgeber

Gieb, Klaus Dr.
Lehrstuhl für Laserphysik
Hampel, Frank Dr.
Lehrstuhl für Organische Chemie I
Heinemann, Frank Dr.
Lehrstuhl für Anorganische und Allgemeine Chemie
Müller, Paul Prof. Dr.
Lehrstuhl für Experimentalphysik
Saalfrank, Rolf Prof. Dr.
Naturwissenschaftliche Fakultät
Scheurer, Andreas Dr.
Lehrstuhl für Anorganische und Allgemeine Chemie
Stocker, Michael
Lehrstuhl für Experimentalphysik


Zitierweisen

APA:
Scheurer, A., Ako, A.M., Saalfrank, R., Heinemann, F., Hampel, F., Petukhov, K.,... Müller, P. (2010). Synthesis, magnetic properties, and STM spectroscopy of cobalt(II) Cubanes [Co(II) (4)(Cl)(4)(HL)(4)]. Chemistry - A European Journal, 16(16), 4784-4792. https://dx.doi.org/10.1002/chem.200902578

MLA:
Scheurer, Andreas, et al. "Synthesis, magnetic properties, and STM spectroscopy of cobalt(II) Cubanes [Co(II) (4)(Cl)(4)(HL)(4)]." Chemistry - A European Journal 16.16 (2010): 4784-4792.

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