Abstract
In the presence of BF 3 ·Et 2 O, the molybdenum-η 3 -allyl complex [Mo(η 5 -C 5 H 5 )(CO) 2 {η 3 -anti-1-Me, 2-(CH 2 =CPh)C 3 H 3 }] reacts with benzaldehyde, methyl vinyl ketone and acetone to give the corresponding η 4 - trimethylenemethane cations; the crystal structure of a pyran complex generated from such cations and of a related complex are reported.