It'd certainly sterilize the vertebrate part of the biosphere: a significant part of its chemical composition (per the paper) should theoretically be CO and HCN. "Hypervolatiles" is the term the paper uses—primordial evils that can only exist in the coldest outer reaches of the Oort cloud, far away from the star that evaporates them.

I don't know the exact numbers, but for water ice the "frost line" is at about 3 au (between Mars and Jupiter)[0]—the line inside which icy comets and ice moons, like Europa, can't form. Presumably there's analogous zones for the increasingly volatile cryogenic ices, going out into the most distant regions—a solid carbon dioxide line, a carbon monoxide line, a cyanide line... The surface of Pluto, for example, is mostly solid nitrogen, with parts of solid methane and solid carbon monoxide [1].

[0] https://en.wikipedia.org/wiki/Frost_line_(astrophysics)

[1] https://en.wikipedia.org/wiki/Pluto#Geology

Nary a username more apt.

I don't think anything beyond the elemental composition of the impactor would matter much since the impact would heat it to a temperature at which it would be in chemical thermodynamic equilibrium, regardless of what its initial molecular composition was.