Double half-cubane copper(ii) complexes available from copper(ii) 1,1,1,5,5,5-hexafluoropentane-2,4-dionate dissolved in formamides

Abstract

Tetranuclear copper(II) complexes were obtained after simply dissolving [Cu(hfac)₂] in formamide–methanol mixed solvents (Hhfac = 1,1,1,5,5,5-hexafluoropentane-2,4-dione). X-Ray diffraction studies revealed that they possessed a tetranuclear double half-cubane core sandwiched with two trianionic ligands from 2,4,6-tris(trifluoromethyl)tetrahydropyran-2,4,6-triol (H₃ttpt). Complexes [Cu₄(ttpt)₂(hfac)₂(dmf)_2.5], [Cu₄(ttpt)₂(tfa)₂(def)₄], and [Cu₄(ttpt)₂(hfac)₂(H₂O)₄](fa) were prepared from N,N-dimethylformamide(dmf)–MeOH, N,N-diethylformamide (def)–MeOH, and formamide(fa)–MeOH (Htfa = trifluoroacetic acid), respectively. A possible mechanism is proposed where a templated aldol-type reaction takes place between hfac and 1,1,1-trifluoroacetonate. Magnetic measurements revealed the presence of antiferromagnetic interaction in the Cu₄O₆ core.