A crossed-beam study of the reaction of CN + D2. Is CN really a spectator bond?

The doubly differential cross sections for the title reaction were measured in a crossed-beam apparatus. The product c.m. angular distributions were sharply backward but showed non-negligible contributions in the forward hemisphere. Contrary to conventional wisdom, these sideways/forward scatterings decrease with a slight increase in initial collision energies. In addition, their product translational energy distributions also displayed a strikingly sensitive dependence on the collision energies. Two possible scenarios were speculated. Both casted some doubts about the subtle role the CN radical played in this reaction as posed in the title.