New synthesis of μ-allenylidene complexes from dimolybdenum carbenium ions crystal structure of 5-C5H5)(CO)2>2(μ,η2-C=C=C6H10)>

Article abstract of DOI:10.1016/0022-328X(94)05117-T

A selective abstraction of the acetylenic proton of cationic allenyl complexes <2(μ-η²,η³-HC<*>CCR¹R²)> (Cp<*>η⁵-C5H5) by using the acetylide LiC<*>CC(CH3)=CH2 gives rise to allenylidene complexes 2-C=C=CR¹R²)> ( (1b); R¹ = R² = CH3, (2b); R¹ = H, R² = C2H5 (3b); R¹ = H, R² = CH3 (4b); R¹ = R² = H (5b); R¹ = CH3, R² = C6H5 (6c)).Compounds 3b and 4b exist as two isomers while for 6c the formation reaction is stereoselective.The crystal structure of 2-C=C=C6H10)> (1b) has been determined.Keywords: Molybdenum; Allenylidene cpxs; Acetylide; X-ray structure; Cyclopentadienyl