Li Ru-Yin, Wang Xin-Yi, Liu Tao, Xu Hong-Bin, Zhao Fei, Wang Zhe-Ming, Gao Song
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.
Inorg Chem. 2008 Sep 15;47(18):8134-42. doi: 10.1021/ic800570a. Epub 2008 Aug 16.
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.
通过使用具有可变构象的合适共配体endi（1,2-(四唑-1-基)乙烷）），我们通过调整配体/金属的化学计量比和溶液浓度，合成了三种新的叠氮桥联Co(2+)化合物，其分子式分别为Co(endi)(N3)2（1,3）和Co(endi)2(N3)2（2）。所有化合物均已通过结构和磁性表征。在所有三种结构中，叠氮离子采用端对端模式将Co(2+)中心连接成一维链（1）和二维（4,4）层（2和3）。endi共配体在化合物1中采用反式构象，在化合物2和3中采用gauche构象。通过桥联endi连接，化合物1中的一维链和化合物3中的二维层得以扩展，从而使化合物1形成最终的二维层，化合物3形成三维网络，而在化合物2中，endi仅作为端基配体来分隔二维层。化合物1由双端对端叠氮桥联的一维Co(2+)链组成，这些链通过反式endi连接成二维层，并通过氢键进一步扩展为三维框架。化合物2是由端对端叠氮离子连接的二维（4,4）层。gauche端基endi配体作为端基配体将相邻层彻底分隔开。化合物3具有与化合物2类似的（4,4）二维层，并且这些层通过gauche endi进一步扩展为三维网络。磁性研究表明，化合物3是反铁磁耦合的，化合物2是一种弱铁磁体，其临界温度为22 K，与先前报道的二维叠氮桥联Co(2+)化合物相比相当高。
