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Article

Extended Triple-Bridged Ni(II)- and Co(II)-Hydroxamate Trinuclear Complexes: Synthesis, Crystal Structures, and Magnetic Properties

Supporting Info

Z. Tomkowicz^†, S. Ostrovsky^‡, H. Müller-Bunz^§, A. J. Hussein Eltmimi^§, M. Rams^†, D. A. Brown^§ and W. Haase*^∥

Institute of Physics, Jagiellonian University, Reymonta 4, 30-059 Kraków, Poland, Institute of Applied Physics, Academy of Sciences of Moldova, Academy str. 5, MD-2028 Chisinau, Moldova, Department of Chemistry, Centre for Synthesis and Chemical Biology, Convay Institute of Biomolecular and Biomedical Research, University College Dublin, Belfield, Dublin 4, Ireland, and Eduard-Zintl-Institute of Inorganic and Physical Chemistry, Darmstadt University of Technology, Petersenstrasse 20, 64287 Darmstadt, Germany

Inorg. Chem., 2008, 47 (15), pp 6956–6963

DOI: 10.1021/ic800264y

Publication Date (Web): July 2, 2008

†

Jagiellonian University.

‡

Academy of Sciences of Moldova.

University College Dublin.

* To whom correspondence should be addressed. E-mail: haase@chemie.tu-darmstadt.de.

∥

Darmstadt University of Technology.

Abstract

Crystal structures of new trinuclear complexes [Ni₃(μ-OAc_F)₄(μ-AA)₂(tmen)₂], [Ni₃(μ-OAc_F)₄(μ-BA)₂(tmen)₂], and [Co₃(μ-OAc_F)₄(μ-BA)₂(tmen)₂] have been determined (OAc_F = CF₃COO⁻, AA = acetohydroxamate anion, BA = benzohydroxamate anion, tmen = N,N,N′,N′-tetramethylethylenediamine). In each structure, the metal ions have distorted octahedral coordination and are triply bridged by one hydroxamate and two trifluoroacetate bridges. Magnetic properties of these compounds and of relative [Co₃(μ-OAc_F)₄(μ-AA)₂(tmen)₂] were studied by susceptibility and magnetization measurements. It was shown that for nickel trimers the intramolecular magnetic coupling is weak ferromagnetic in the case of the complex with the AA group, and there is nearly no coupling in the case with BA group. Rather large zero field splitting was obtained for the distorted octahedral environments of the terminal nickel ions. The cobalt trimers were additionally studied by magnetic circular dichroism (MCD) measurements. The exchange interaction of the cobalt complexes is antiferromagnetic.