Synthesis and structural characterization of copper(II) bishexafluoroacetylacetonate complexes with N-donor ligands

The reactions of Cu(hfac)2 with different N-donor ligands such as 2-ethynylpyridine and imidazole give copper complexes Cu(hfac)2(ethynylpyridine) (1) and Cu(hfac)2(ImH)2 (2), respectively. The reaction of Cu(hfac)2 · (ethynylpyridine) (1) and ethynylpyridine with oxygen in tmeda (tmeda = N,N,N′,N′-tetramethylethylenediamine) in the presence of copper(I) chloride gives Cu(hfac)2(tmeda) (3). Finally, [Cu(hfac)2(H2O)]2(μ-TCNE) (4) was prepared by reaction of Cu2O on the free acid β-diketone in the presence of TCNE (TCNE = tetracyanoethylene) (ratio 1.5:1:1), under an atmosphere of oxygen-free Ar. The previously synthesized Cu(hfac)TCNE proceeded further reaction by disproportionation, yielding [Cu(hfac)2(H2O)]2(μ-TCNE). All new compounds have been structurally characterized and their thermal properties were examined by thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC).