Indexed by:期刊论文

Date of Publication:2014-01-01

Journal:EUROPEAN JOURNAL OF INORGANIC CHEMISTRY

Included Journals:SCIE、Scopus

Volume:2014

Issue:2

Page Number:384-391

ISSN No.:1434-1948

Key Words:Cluster compounds; Magnetic properties; Cobalt; Lanthanides; Solvent effects

Abstract:Two series of tetranuclear [Ln(2)Co(2)] clusters were built from the same [Co(CDTA)](2-) building blocks but have different metal skeletons: square 1Ln compounds {[Ln(2)Co(2)(CDTA)(2)((4)-OH)(DMF)(2)(H2O)(6)]<bold>ClO(</bold>4)1.5H(2)O; Ln = La, Gd, and Dy} with a (4)-OH- bridged Ln-Co-Ln-Co arrangement, and two (3)-OH--bridged butterfly 2Ln compounds {[Ln(2)Co(2)(CDTA)(2)((3)-OH)(2)(H2O)(6)]6H(2)O; Ln = Gd, Tb, Dy, and Y} with two Ln(3+) ions as the body and two Co2+ ions as wings. They were prepared from the solvothermal reactions of trans-1,2-diaminocyclohexane-N,N,N,N-tetraacetic acid (H(4)DCTA), Ln(ClO4)(3), and Co(ClO4)(2) in DMF/H2O or H2O solvent. Their syntheses are mainly controlled by the solvent and the radii of Ln(3+) ions. Light Ln(3+) ions with big radii are favorable for the formation of square complexes, whereas heavy Ln(3+) ions (including Y3+) with small radii promote the formation of butterfly ones. Remarkably, the middle Ln(3+) ions are favorable for the formation of both structures, and in these cases the reactions are controlled by solvent (H2O or H2O + DMF). Magnetic analyses reveal the antiferromagnetic interactions between the two Co2+ ions in 1La and 2Y. Interestingly, other butterfly clusters (2Gd, 2Tb, 2Dy) show dominant ferromagnetic interactions, whereas the other square clusters (1Gd, 1Dy) show overall antiferromagnetic interactions. Details of the magnetic interaction between the metal ions are discussed.