10.1016/0304-5102(88)85100-9
The study investigates the reactions of benzylidene(pentacarbonyl)tungsten complexes, specifically (CO)5W=C(C6H4R-p)H (where R = H, Me), with various alkynes such as diethylaminopropyne (Et2NC2CMe) and 2-butyne. The benzylidene complexes act as highly reactive and electrophilic reagents. When reacting with diethylaminopropyne, the C≡C bond of the alkyne inserts into the W=C bond of the complex, forming a new complex (CO)5W=C(NEt2)-C(Me)=C(C6H4R-p)H. With 2-butyne, the reaction yields (CO)5W[MeC≡CMe] and various coupling products, but no polymerization occurs. However, when t-BuC≡CH is used in excess, rapid polymerization is observed, and a mechanism involving the initial formation of a vinylidene complex is proposed. The study also explores the thermolysis of terminal benzylidene complexes in inert solvents, which leads to the formation of benzylidene-bridged bis(pentacarbonyltungsten) complexes that can initiate the polymerization of 2-butyne. The research provides insights into the reactivity of benzylidene complexes and their potential as initiators for alkyne polymerization.