Department of Chemistry, Research Institute for Natural Sciences, Korea University, Seoul 136-713, Korea.
Inorg Chem. 2011 Nov 7;50(21):10777-85. doi: 10.1021/ic2013232. Epub 2011 Oct 6.
Three one-dimensional coordination polymers Mn(L)(N(3)) [L = L1 (1), L2 (2), L3 (3); L1H(2) = N,N'-bis(5-chlorosalicylideneiminato)-1,3-diaminopentane, L2H(2) = N,N'-bis(5-bromosalicylideneiminato)-1,3-diaminopentane, L3H(2) = N,N'-bis(5-bromosalicylideneiminato)-1,3-diamino-2-dimethylpropane] bridged by end-to-end azides were prepared. The crystal systems differ according to the Schiff bases used. Each Mn atom adopts a typical Jahn-Teller distortion. The helicity of the chains occurs in a racemic manner only for 2. No noncovalent forces are relevant in 2, while π-π contacts are visible in 1 and 3. Magnetic measurements show the presence of apparent spin canting. Complexes 1 and 3 exhibit a field-induced metamagnetic transition from an antiferromagnetic state to a weak ferromagnetic phase, whereas 2 embraces a field-induced two-step magnetic phase transition. The critical temperature is observed at 38 K for 2, which is relatively higher than those for 1 (11 K) and 3 (10 K). The pronounced long-range order may contribute from intrachain exchange couplings and through-space dipolar interactions between adjacent chains.
三种一维配位聚合物Mn(L)(N(3)) [L = L1 (1), L2 (2), L3 (3); L1H(2) = N,N'-双(5-氯水杨醛亚胺基)-1,3-二氨基戊烷，L2H(2) = N,N'-双(5-溴水杨醛亚胺基)-1,3-二氨基戊烷，L3H(2) = N,N'-双(5-溴水杨醛亚胺基)-1,3-二氨基-2-二甲基丙烷]通过末端叠氮桥联而成。晶体系统根据所使用的席夫碱而有所不同。每个 Mn 原子采用典型的 Jahn-Teller 畸变。只有 2 中的链以外消旋方式发生螺旋性。2 中没有非共价力相关，而 1 和 3 中可见π-π 接触。磁测量显示存在明显的自旋倾斜。复合物 1 和 3 表现出从反铁磁态到弱铁磁相的场诱导顺磁转变，而 2 则具有场诱导的两步磁相变。2 的临界温度在 38 K 处观察到，相对高于 1（11 K）和 3（10 K）。明显的长程有序可能来自于链内交换耦合和相邻链之间的空间偶极相互作用。
