STRUCTURAL RELATIONSHIPS BETWEEN DICOPPER DIACETYLIDE (CU-C-C-C-C-CU)AND DICOPPER ACETYLIDE (CU-C-C-CU)

Dicopper diacetylide Cu-C=C-C=C-Cu, prepared from butadiyne has been s tudied by FT-IR spectroscopy in comparison to dicopper acetylide Cu-C= C-Cu. Upon ageing by exposure to air at room temperature, Cu-C=C-Cu ha s been transformed into Cu-C=C-C=C-Cu as demonstrated by FT-TR spectro scopy and this compound is further transformed on standing in air. A s pecial kind of solid state oxidative coupling reaction occurs so that polyynes chains are formed in these aged solids. It is shown that the FT-IR spectrum of copper acetylide prepared from ammonia solutions of Cu+ and Cu2+ ions is comparable to that of air oxidized Cu-C=C-Cu (and Cu-C=C-C=C-Cu) prepared exclusively from Cd ions in presence of a red ucing agent demonstrating that Cu2+ ions display the same oxidizing ef fect as oxygen causing coupling reactions in solution and producing Cu -C=C-C=C-Cu. Cu-C=C-Cu oxidized at 60-70 degrees C with CuCl2 produces a product which could be formulated as Cu(C=C)(20)Cu; FT-IR absorptio n at 1950 cm(-1) could suggest the presence of cumulenic carbon chain although acetylenic carbon chains cannot be excluded completely.