Synthesis, structure, and magnetism of three azido-bridged Co2+ compounds with a flexible coligand 1,2-(tetrazole-1-yl)ethane.
By utilizing suitable coligand endi (1,2-(tetrazole-1-yl)ethane)) with variable conformations, we synthesized three new azido-bridged Co(2+) compounds with molecular formulas Co(endi)(N3)2 (1, 3) and Co(endi)2(N3)2 (2) by tuning the stoichiometric ratio of ligand/metal and the concentration of the solution. All of the compounds have been characterized structurally and magnetically. In all three structures, the azide ions use the end-to-end mode to link the Co(2+) centers to the 1D chain (1) and 2D (4,4) layers (2 and 3). The endi coligands adopt a trans conformation in compound 1 and a gauche conformation in compounds 2 and 3. Linked by bridging endi, the 1D chains in compound 1 and 2D layers in compound 3 are extended, resulting in the final 2D layer for compound 1 and the 3D network for compound 3, whereas in compound 2, the endi acts as only a terminal ligand to separate the 2D layers. Compound 1 consists of dual end-to-end azido-bridged 1D Co(2+) chains that are linked by trans endi into a 2D layer and are further extended to a 3D framework through H bonds. Compound 2 is a 2D (4,4) layer that is connected by end-to-end azido ions. The gauche endi ligands act as terminal ligands to separate the neighboring layers thoroughly. Compound 3 has a (4,4) 2D layer that is similar to that of compound 2, and these layers are further extended to a 3D network through gauche endi. The magnetic investigation shows that compound 3 is antiferromagnetically coupled and compound 2 is a weak ferromagnet with a critical temperature of 22 K, which is quite high compared with that of the previously reported 2D azido-bridged Co(2+) compounds.
Li
Ru-Yin
RY
Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, PRC.
Wang
Xin-Yi
XY
Liu
Tao
T
Xu
Hong-Bin
HB
Zhao
Fei
F
Wang
Zhe-Ming
ZM
Gao
Song
S