Titanium-based molecular squares and rectangles: syntheses by self-assembly reactions of titanocene fragments and aromatic N-heterocycles.
Titanium-based molecular squares and rectangles: syntheses by self-assembly reactions of titanocene fragments and aromatic N-heterocycles.
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DOI：
10.1002/chem.200400880
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发表时间：
2005-01
期刊：
影响因子：
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通讯作者：
Susanne Kraft;E. Hanuschek;R. Beckhaus;D. Haase;W. Saak
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文献类型：
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作者：
Susanne Kraft;E. Hanuschek;R. Beckhaus;D. Haase;W. Saak
本文报道了钛化合物作为超分子多边形结构单元的潜力。低价茂钛单元与N-杂环桥联配体的自组装反应合成了新型钛基超分子正方体。吡嗪（3）、4，4 '-联吡啶（4）和四嗪（5）用作桥连配体，乙炔配合物[Cp 2 Ti {eta 2-C2（SiMe 3）2}]（1）和[（tBuCp）2 Ti {eta 2-C2（SiMe 3）2}]（2）用作二茂钛碎片的来源。通过逐步还原二氯二茂钛[Cp（2）TiCl 2]和[（tBuCp）2 TiCl 2]并连续配位两种不同的桥连配体可以合成分子矩形。所得配合物是含有弯曲茂金属角单元的分子矩形的第一个实例。四核化合物的单晶X射线分析揭示了固态分子多边形的几何性质。配位和自由配体的键长和键角的比较揭示了低价钛化合物中桥连配体的还原状态。这些新的，高度的空气和水分敏感的化合物的合成和性能进行了讨论。
This paper reports on the potential of titanium compounds as building blocks for supramolecular polygons. Self-assembly reactions of low-valent titanocene units and N-heterocyclic bridging ligands lead to novel titanium-based supramolecular squares. Pyrazine (3), 4,4'-bipyridine (4), and tetrazine (5) were used as bridging ligands, and the acetylene complexes [Cp2Ti{eta2-C2(SiMe3)2}] (1) and [(tBuCp)2Ti{eta2-C2(SiMe3)2}] (2) as sources of titanocene fragments. Molecular rectangles can be synthesized by stepwise reduction of the titanocene dichlorides [Cp(2)TiCl2] and [(tBuCp)2TiCl2] and consecutive coordination of two different bridging ligands. The resulting complexes are the first examples of molecular rectangles containing bent metallocene corner units. Single-crystal X-ray analyses of the tetranuclear compounds revealed the geometric properties of the molecular polygons in the solid state. Comparison of bond lengths and angles in coordinated and free ligands reveals the reduced state of the bridging ligand in the low-valent titanium compounds. The syntheses and properties of these novel, highly air- and moisture-sensitive compounds are discussed.