Gas-phase reaction of tungsten dimer with NH3 and C2H4 at room temperature

Absolute reaction rate constants of ground-state tungsten dimer W2(X) with C2H4 (as a typical π-acceptor) and NH3 (as a typical σ-donor) were measured in the gas phase at room temperature. For the production of the tungsten dimer, a 266-nm multiphoton decomposition of W(CO)6 was used. W2(X) was observed to react with C2H4 faster than NH3. This chemical reactivity pattern for W2(X) differs much from that of the isovalent Mo2(X) molecule, which was previously reported to be reactive to a σ-donor but not to a π-acceptor. It is suggested that this is the result of relativistic effects in the heavy metal dimer, W2.