Critical Role of External Axial Ligands in Chirality Amplification of trans-Cyclohexane-1,2-diamine in Salen Complexes
Critical Role of External Axial Ligands in Chirality Amplification of trans-Cyclohexane-1,2-diamine in Salen Complexes
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DOI：
10.1021/ja904635n
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发表时间：
2009-09-02
影响因子：
15
通讯作者：
Fujii, Hiroshi
中科院分区：
文献类型：
--
作者：
Kurahashi, Takuya;Hada, Masahiko;Fujii, Hiroshi
以反式-1，2-环己二胺为手性骨架，合成了一系列具有不同轴向配体（L = Cl，NO3，N3-和OCH 2CF 3）的Mn-Ⅳ（salen）（L）（2）配合物，研究了金属salen配合物的构象性质. X-射线晶体结构表明，Mn-IV（salen）（OCH 2CF 3）（2）和Mn-IV（salen）（N-3）（2）由于反式环己烷-1，2-二胺的偏置，两个水杨醛环中的一个向上，另一个向下，呈阶梯状构象，这与Mn-IV（salen）（Cl）（2）相对平坦的固态构象形成鲜明对比。Mn-IV（salen）（L）（2）的CH_2Cl_2溶液显示出强度按L = Cl
A series of Mn-IV(salen)(L)(2) complexes bearing different external axial ligands (L = Cl, NO3, N-3, and OCH2CF3) from chiral salen ligands with trans-cyclohexane-1,2-diamine as a chiral scaffold are synthesized, to gain insight into conformational properties of metal salen complexes. X-ray crystal structures show that Mn-IV(salen)(OCH2CF3)(2) and Mn-IV(salen)(N-3)(2) adopt a stepped conformation with one of two salicylidene rings pointing upward and the other pointing downward due to the bias from the trans-cyclohexane-1,2-diamine moiety, which is in clear contrast to a relatively planar solid-state conformation for Mn-IV(salen)(Cl)(2). The CH2Cl2 solution of Mn-IV(salen)(L)(2) shows circular dichroism of increasing intensity in the order L = Cl < NO3