The New Carbodiimide Li2Gd2Sr(CN2)5 Having a Crystal Structure Related to That of Gd2(CN2)3

The new carbodiimide compounds Li2RE2Sr(CN2)5 (RE = Sm, Gd, Eu, Tb) were prepared by a straight forward solid state metathesis reaction of REF3, SrF2, and Li2(CN2) at around 600 degrees C. The crystal structure of Li2Gd2Sr(CN2)5 was solved based on X-ray single-crystal diffraction data. Corresponding Li2RE2Sr(CN2)5 compounds were analyzed by isotypic indexing of their powder patterns. The crystal structure of Li2Gd2Sr(CN2)5 can be well related to that of Gd2(CN2)3, because both structures are based on layered structures composed of close packed layers of [N=C=N]2 sticks, alternating with layers of metal ions. The crystal structure of Li2Gd2Sr(CN2)5 can be considered to contain an ABC layer sequence of [N = C=N]2 layers with the interlayer voids being occupied by (three) distinct types of cations.