Structures and Dynamic Behavior of Large Polyhedral Coordination Cages: An Unusual Cage-to-Cage Interconversion
Structures and Dynamic Behavior of Large Polyhedral Coordination Cages: An Unusual Cage-to-Cage Interconversion
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DOI：
10.1021/ja107403p
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发表时间：
2011-02-02
影响因子：
15
通讯作者：
Ward, Michael D.
中科院分区：
文献类型：
--
作者：
Stephenson, Andrew;Argent, Stephen P.;Ward, Michael D.
双-双齿桥连配体L {α，α '-双-[3-（3-甲基苯基）-N-甲基-N-（2-甲基苯基）-N-甲基-N-（2-甲基苯基）-N-甲基-（2-吡啶基）吡唑-1-基]-1，4-二甲基苯}与过渡金属二价阳离子反应形成一系列基于2 M：其中金属离子占据多面体的每个顶点，桥接配体位于沿着每个边，并且所有金属离子都是八面体配位的。而Ni（II）配合物[Ni 8L 12]-（BF 4）（12）（SiF 6）（2）是我们以前见过的八核立方笼型，Cu（II），Zn（II）和Cd（II）配合物形成新的结构类型。[Cu 6L 9]（BF 4）（12）是一个不寻常的三方棱柱笼的例子，Zn（II）和Cd（II）形成前所未有的十六核笼[M16 L24]X-32（X = ClO 4或BF 4），其核心是一个斜四帽截顶四面体。Cu 6L 9和M16 L24笼都是基于环状螺旋M3 L3亚基，其可以被认为是三角形“面板”，其中笼是通过这些（同手性）面板与另外的桥接配体以不同方式互连而构建的。而[Cu_6L_9]（BF_4）（12）在溶液中稳定（通过电喷雾质谱法，ES-MS）并且通过Cu（BF 4）（2）和L在溶液中以正确的比例结合而快速形成，在结晶时形成的十六核笼[Cd 16 L24]（BF 4）（32）在溶液中经过几周的时间缓慢重排为三棱柱[Cd 6L 9]（BF 4）（12），其基于其H-1 NMR谱明确地鉴定。类似地，Cd（BF 4）（2）和L以2：3的比例组合产生主要成分为三棱柱[Cd 6L 9]（BF 4）（12）的混合物。因此，六核三棱柱是由溶液中Cd（II）和L以2：3的比例结合产生的热力学产物，并且由金属和配体的组装（分钟）和Cd-16笼的重排（周）产生;大笼[Cd 16 L24]（BF 4）（32）作为溶液中物质混合物的次要组分存在，但优先结晶。
The bis-bidentate bridging ligand L {alpha,alpha'-bis-[3-(2-pyridyl)pyrazol-1-yl]-1,4-dimethylbenzene}, which contains two chelating pyrazolyl-pyridine units connected to a 1,4-phenylene spacer via flexible methylene units, reacts with transition metal dications to form a range of polyhedral coordination cages based on a 2M:3 L ratio in which a metal ion occupies each vertex of a polyhedron, a bridging ligand lies along every edge, and all metal ions are octahedrally coordinated. Whereas the Ni(II) complex [Ni8L12]-(BF4)(12)(SiF6)(2) is an octanuclear cubic cage of a type we have seen before, the Cu(II), Zn(II), and Cd(II) complexes form new structural types. [Cu6L9](BF4)(12) is an unusual example of a trigonal prismatic cage, and both Zn(II) and Cd(II) form unprecedented hexadecanuclear cages [M16L24]X-32(X = ClO4 or BF4) whose core is a skewed tetracapped truncated tetrahedron. Both Cu6L9 and M16L24 cages are based on a cyclic helical M3L3 subunit that can be considered as a triangular "panel", with the cages being constructed by interconnection of these (homochiral) panels with additional bridging ligands in different ways. Whereas [Cu6L9](BF4)(12) is stable in solution (by electrospray mass spectrometry, ES-MS) and is rapidly formed by combination of Cu(BF4)(2) and L in the correct proportions in solution, the hexadecanuclear cage [Cd16L24](BF4)(32) formed on crystallization slowly rearranges in solution over a period of several weeks to the trigonal prism [Cd6L9](BF4)(12), which was unequivocally identified on the basis of its H-1 NMR spectrum. Similarly, combination of Cd(BF4)(2) and L in a 2:3 ratio generates a mixture whose main component is the trigonal prism [Cd6L9](BF4)(12). Thus the hexanuclear trigonal prism is the thermodynamic product arising from combination of Cd(II) and L in a 2:3 ratio in solution, and arises from both assembly of metal and ligand (minutes) and rearrangement of the Cd-16 cage (weeks); the large cage [Cd16L24](BF4)(32) is present as a minor component of a mixture of species in solution but crystallizes preferentially.