Synthesis and characterization of alkynes β-diketonate copper(I) complexes

The reactions of 1,3,5-tris-(trimethylsilylethynyl)benzene (1) with Cu2O and 1,1,1,5,5,5,-hexafluoroacetylacetone in alkyne to Cu ratios 1:0.5, 1:1 and 1:3 in CH2Cl2 at room temperature give copper complexes (η2-1,3,5-tris(trimethylsilylethynyl)benzene)(Cu(hfac)) (2), (η2:η2-1,3,5-tris(trimethylsilylethynyl)benzene)(Cu(hfac))2 (3) and (η2:η2:η2-(1,3,5- tris(trimethylsilylethynyl)benzene))2(Cu(hfac))3(4), respectively. In the same conditions, 2,5-bis-(trimethylsilylethynyl)thiophene (5) reacts with 0.5 or 1 equiv. of Cu2O to give (η2:η2-2,5-bis(trimethylsilylethynyl)thiophene)(Cu(hfac)) (6) and (η2:η2-2,5-bis(trimethylsilylethynyl)thiophene)(Cu(hfac))2 (7), respectively, and 1,4-bis(trimethylsilyl)-1,3-butadiyne (8) with 0.5 equiv. of Cu2O give (η2:η2-1,4-bis(trimethylsilyl)-1,3-butadiyne)(Cu(hfac))2(9). All the new compounds have been characterized by analytical and spectroscopic methods and their thermal properties were examined by thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC).