THEORETICAL-STUDY OF THE METATHESIS-LIKE REACTION BETWEEN DITUNGSTEN HEXAALKOXIDES AND ALKYNES

Density-functional calculations have been carried Out On a metathesis- like reaction between W-2(OR)(6) (R = alkyl) and alkynes to give tungs ten alkylidyne complexes. Two possible pathways have been taken into c onsideration: (i) a parallel approach between the reactants to give 1, 2 -ditungstenacyclobutadiene; (ii) a perpendicular approach to yield a ditungstenatetrahedrane which then flattens giving a 1,3-ditungstenac yclobutadiene. The electronic structure of the compounds involved in t he reaction, as well as several energy profiles corresponding to the f ormation and decomposition of these species, have been investigated in order to study the thermodynamics and kinetics of the metathesis-like reaction. The inclusion of relativistic effects is crucial in order t o understand how the reaction proceeds.