Figure : Ambiguous hydrogen insertion. Transformation of hydrogen atoms in two scenarios, where the directionality of hydrogen transfer is reversed between instances. In the first instance (A), hydrogen transfers from a hydroxy (OH) group to a nitrogen in a cyanide (CN) group, and from a benzene ring to a nitrogen in a hydroxylamine (N OH) group. In the second instance (B), hydrogen transfers from a benzene ring to a nitrogen in a cyanide group and from a hydroxy group to a nitrogen in a hydroxylamine group. Instance A is chemically accurate, leading to the formation of combinatorial ITS, characterized by fourand six-membered cycles.