Novel pyrazolate-based copper(II) [2 x 2] grid complexes: Synthesis, structure and properties

Summary, in English

5-Acetyl-substituted pyrazole-3-carboxylic acid (H2L) forms [2 x 2] grid-like tetranuclear Cu(II) complexes with four five-coordinated copper(II) ions bridged by pyrazolate groups. Despite a significant dissociation of [Cu4L4(H2O)(4)]center dot 4H(2)O (1) in aqueous solution(1), it was possible to substitute the coordinated water molecules by pyridine ligands or azide anions. The resulting tetranuclear complexes [Cu4L4Py4]center dot 2H(2)O (2) and Na-4[Cu4L4(N-3)(4)]center dot 7MeOH (3) were isolated and studied by X-ray diffraction analysis. In 2 and 3 the azide anions or pyridine molecules complete the distorted square-pyramidal coordination of each copper(II) center. Magnetic susceptibilities of the obtained compounds have been measured by SQUID techniques. Simulation of the data using a Heisenberg spin Hamiltonian approach showed that the bridges between the metals mediate weak intramolecular antiferromagnetic coupling (J in the range -13.3 to -17.1 cm (1)) and lead to a singlet ground state in all cases. (C) 2012 Elsevier B.V. All rights reserved.

• Author: Sergey O. Malinkin; Yurii S. Moroz; Larysa V. Penkova; Matti Haukka; Agnieszka Szebesczyk; Elzbieta Gumienna-Kontecka; Vadim A. Pavlenko; Ebbe Nordlander; Franc Meyer; Igor O. Fritsky
• Department/s: Chemical Physics
• Publishing year: 2012
• Language: English
• Pages: 322-330
• Publication/Series: Inorganica Chimica Acta
• Volume: 392
• Links: http://dx.doi.org/10.1016/j.ica.2012.03.021
• Document type: Journal article
• Publisher: Elsevier
• Topic: Atom and Molecular Physics and Optics
• Keywords: Pyrazole ligands; Copper(II); Grid complexes; Magnetic properties
• Status: Published
• ISBN/ISSN/Other: ISSN: 0020-1693