Products of hydrogen
cyanide (HCN) reactivity are suspected to
play important roles in astrochemistry and, possibly, the origin of
life. The composition, chemical structure, and mechanistic details
for formation of products from HCN’s self-reactions have, however,
proven elusive for decades. Here, we elucidate base-catalyzed reaction
mechanisms for the formation of diaminomaleonitrile and polyimine
in liquid HCN using ab initio molecular dynamics simulations. Both
materials are proposed as key intermediates for driving further chemical
evolution. The formation of these materials is predicted to proceed
at similar rates, thereby offering an explanation of how HCN’s
self-reactions can diversify quickly under kinetic control. Knowledge
of these reaction routes provides a basis for rationalizing subsequent
reactivity in astrochemical environments such as on Saturn’s
moon Titan, in the subsurface of comets, in exoplanet atmospheres,
and on the early Earth.