Crystal Structures of Extended Europium Cyanamide−Carbodiimide Compounds Derived from Different Reaction Conditions:  Temperature-Controlled Syntheses of In_0.08Eu₄(NCN)₃I₃, Eu₈I₉(CN)(NCN)₃, and In_0.28Eu₁₂(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_0.08Eu₄(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_0.28Eu₁₂(NCN)₅I_14.91 is characterized by a sandwichlike 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.