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Design of Dinuclear Copper Species with Carboranylcarboxylate Ligands: Study of Their Steric and Electronic Effects

Authors

  • Mònica Fontanet,

    1. Department de Química and Serveis Tècnics de Recerca, Universitat de Girona, Campus de Montilivi, 17071 Girona (Spain), Fax: (+34) 972418150
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  • Adrian-Radu Popescu,

    1. Institut de Ciencia de Materials de Barcelona, ICMAB-CSIC, Campus UAB, 08193 Bellaterra (Spain), Fax:(+34) 93 580 5729
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    • A. R. Popescu is enrolled in the PhD program of the UAB.

  • Xavier Fontrodona,

    1. Department de Química and Serveis Tècnics de Recerca, Universitat de Girona, Campus de Montilivi, 17071 Girona (Spain), Fax: (+34) 972418150
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  • Dr. Montserrat Rodríguez,

    1. Department de Química and Serveis Tècnics de Recerca, Universitat de Girona, Campus de Montilivi, 17071 Girona (Spain), Fax: (+34) 972418150
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  • Dr. Isabel Romero,

    Corresponding author
    1. Department de Química and Serveis Tècnics de Recerca, Universitat de Girona, Campus de Montilivi, 17071 Girona (Spain), Fax: (+34) 972418150
    • Department de Química and Serveis Tècnics de Recerca, Universitat de Girona, Campus de Montilivi, 17071 Girona (Spain), Fax: (+34) 972418150
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  • Prof. Francesc Teixidor,

    Corresponding author
    1. Institut de Ciencia de Materials de Barcelona, ICMAB-CSIC, Campus UAB, 08193 Bellaterra (Spain), Fax:(+34) 93 580 5729
    • Institut de Ciencia de Materials de Barcelona, ICMAB-CSIC, Campus UAB, 08193 Bellaterra (Spain), Fax:(+34) 93 580 5729
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  • Prof. Clara Viñas,

    1. Institut de Ciencia de Materials de Barcelona, ICMAB-CSIC, Campus UAB, 08193 Bellaterra (Spain), Fax:(+34) 93 580 5729
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  • Dr. Núria Aliaga-Alcalde,

    1. ICREA (Institució Catalana de Recerca i Estudis Avançats), Passeig Lluis Companys 23, 08010 Barcelona (Spain)
    2. Departament de Química Inorgànica, Universitat de Barcelona, Diagonal 645, 08028 Barcelona (Spain)
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  • Dr. Eliseo Ruiz

    1. Departament de Química Inorgànica, Universitat de Barcelona, Diagonal 645, 08028 Barcelona (Spain)
    2. Institut de Recerca de Química Teòrica i Computacional Universitat de Barcelona, Diagonal 647, Barcelona 08028 (Spain)
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Abstract

A series of new mononuclear and carboranylcarboxylate-bridged dinuclear copper(II) compounds containing the 1-CH3-2-CO2H-1,2-closo-C2B10H10 carborane ligand (LH) has been synthesized. Reaction of different copper salts with LH at room temperature leads to dinuclear compounds of the general formula [Cu2(μ-L)4(Lt)2] (Lt=thf (1), Lt=H2O (1′)). The reaction of 1 and 1′ with different terminal pyridyl (py) ligands leads to the formation of a series of structurally analogous complexes by substitution of the terminal ligand thf or H2O (Lt=py (2), p-CF3-py (3), p-CH3-py (4), pz (6), and 4,4′-bpy (7)), which maintain the structural Cu2(μ-O2CR)4 core in the majority of the cases except for o-(CH3)2-py, where a mononuclear compound (5) is exclusively obtained. These compounds have been characterized through analytical, spectroscopic (NMR, IR, UV-visible, ESI-MS) and magnetic techniques. X-ray structural analysis revealed a paddle-wheel structure for the dinuclear compounds, with a square-pyramidal geometry around each copper ion and the carboranylcarboxylate ions bridging two copper atoms in synsyn mode. The mononuclear complex obtained with the o-(CH3)2-py ligand presents a square-planar structure, in which the carboranylcarboxylate ligand adopts a monodentate coordination mode. The magnetic properties of the dinuclear compounds 1, 3, 4, and 6 show a strong antiferromagnetic coupling in all cases (J=−261 (1), −255 (3), −241 (4), −249 cm−1 (6)). Computational studies based on hybrid density functional methods have been used to study the magnetic properties of the complexes and also to evaluate their relative stability on the basis of the strength of the bond between each CuII and the terminal ligand.

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