Synthesis and characterization of new transition metal diynyl complexes

The reaction of (η5-C5H5)Mo(CO)(dppe)Cl with LiCCCCSiMe3 yielded (η5-C5H5)(CO)(dppe)MoCCCCSiMe3 (1b) and, as a by-product (η5-C5H5)Mo(CO)(dppe)Br (1a). Treatment of 1b with 0.2 equivalents of tetrabutylammonium fluoride or (η5-C5H5)Mo(CO)(dppe)Cl with HCCCCH gave the terminal butadiyne complex (η5-C5H5)(CO)(dppe)MoCCCCH (2). Complex 2 was deprotonated with sec-BuLi or lithium diisopropylamide, and the resulting anion …