Two diammonium copper azides with similar layerlike magnetic substructures made of chains of serially connected Cu6 rings show cation-modulated magnetism.
We present here the first examples of Cu-azide compounds synthesized by using protonated diamine ions as cationic templates: (dmenH(2))[Cu(6)(N(3))(14)] and (trimenH(2))[Cu(6)(N(3))(14)](dmenH(2)(2+): N,N'-dimethylethylenediammonium; trimenH(2)(2+): N,N,N'-trimethylethylenediammonium). Both compounds possess a similar, rarely observed anionic Cu-azide layer, which consists of [Cu(6)(N(3))(14)(2-)](n) anionic chains linked by asymmetric end-to-end azido bridges. The chain, in turn, is made up of elongated Cu(6) rings, with double and single end-on azido linkages between the square-planar Cu(2+) sites within the ring and double end-on azido bridges serially connecting the rings. The molecular geometry results in ferromagnetic interactions within the Cu-azide layer in both compounds. The interlayer separations are determined by the cations, with the shortest interlayer CuCu separations being 8.016 A for the dmenH(2)(2+) compound and 9.106 A for the trimenH(2)(2+) compound. These different interlayer separations tune the magnetic properties of the two materials. The dmenH(2)(2+) compound displays long-range antiferromagnetic ordering at low temperature and short-range ferromagnetic interaction at high temperature, while only short-range ferromagnetism was observed in the trimenH(2)(2+) compound at 2-300 K.
Liu
Tao
T
Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China.
Yang
Yan-Fei
YF
Wang
Zhe-Ming
ZM
Gao
Song
S