title: Synthesis, structure, and magnetism of three azido-bridged Co2+ compounds with a flexible coligand 1,2-(tetrazole-1-yl)ethane.
abstract: 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.
authors.affiliation: 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.
authors.forename: Ru-Yin
authors.initials: RY
authors.lastname: Li
authors.forename: Xin-Yi
authors.initials: XY
authors.lastname: Wang
authors.forename: Tao
authors.initials: T
authors.lastname: Liu
authors.forename: Hong-Bin
authors.initials: HB
authors.lastname: Xu
authors.forename: Fei
authors.initials: F
authors.lastname: Zhao
authors.forename: Zhe-Ming
authors.initials: ZM
authors.lastname: Wang
authors.forename: Song
authors.initials: S
authors.lastname: Gao