Ligand exchange reactions of a 1,3-butadiene complex of magnesium

The ligand exchange reaction of a diene ligand bound to magnesium was investigated. Reaction of the magnesium-butadiene compound [Mg(C(4)H(6))(thf)(2)](n) (2) with 1,4-diphenyl-1,3-butadiene afforded Mg(s-cis-1,4-diphenyl-1,3-butadiene)(thf)(3) (1) together with butadiene. Similarly, treatment of 2 with 1,6-diphenyl-1,3,5-hexatriene, anthracene, and 1,3,5,7-cyclooctatetraene afforded the corresponding magnesium adducts Mg(1,6-diphenyl-1,3,5-hexatriene)(thf)(3) (3), Mg(anthracene)(thf)(3) (4), and Mg(cot)(thf)(2.5) (5), respectively, in addition to the liberated butadiene. Reaction of 2 with diphenylacetylene in THF also induced the ligand exchange reaction, resulting in the formation of a diphenylacetylene adduct [Mg(PhC(2)Ph)(thf)](4) (6) of magnesium. (C) 1997 Elsevier Science S.A.