Experimental and theoretical studies of the products of reaction between Ln(hfa)3 and Cu(acac)2 (Ln = La, Y; acac = acetylacetonate, hfa = hexafluoroacetylacetonate)

The new unusual heterobimetallic complex [La(hfa)3Cu(acac)2(H2O)] (I) was obtained in the reaction La(hfa)3·2H2O with Cu(acac)2 in CHCl3. This is the first example of such type of heterobimetallic complexes based on the Cu(acac)2 species. According to the X-ray single crystal analysis, complex I crystallizes in the monoclinic space group P21/c, with a = 12.516(3) Å, b = 17.757(4) Å, c = 17.446(4) Å, β = 93.90(3)° and Z = 4. The structure consists of isolated heterobinuclear molecules with the coordination number of La being 9. The molecules are further assembled into dimers via hydrogen bonds. The theoretical modeling of the structure and the properties of parent monometallic complexes Ln(hfa)3 (Ln = La, Y) and Cu(acac)2 is described. The comparative theoretical study of lanthanide complexes indicates relations in formation of a heterobimetallic complex to the Lewis acidity of original monometallic complexes. In particular, the Lewis acidity and charge of the central metal ion in Ln(hfa)3 are the key parameters accounting for the formation of [Ln(hfa)3Cu(acac)2].