Crystal structures of extended europium cyanamide-carbodiimide compounds derived from different reaction conditions: temperature-controlled syntheses of In(0.08)Eu4(NCN)3I3, Eu8I9(CN)(NCN)3, and In(0.28)Eu12(NCN)5I(14.91).

A different thermal treatment of identical reactants (EuI2, NaCN, NaN3, and InI) leads to the formation of the three title compounds. In(0.08)Eu4(NCN)3I3 is isotypic with the reported LiEu4(NCN)3I3, Eu8I9(CN)(NCN)3 represents the first mixed cyanide-cyanamide rare-earth compound, and In(0.28)Eu12(NCN)5I(14.91) is characterized by a sandwich-like stacking motif involving Eu4-NCN double layers stuffed by a layer of vertex-sharing InI6 octahedra. The redox behavior of In is the main factor that leads to alternative product formation as a function of the temperature.