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Titanium‐Based Molecular Squares and Rectangles: Syntheses by Self‐Assembly Reactions of Titanocene Fragments and Aromatic N‐Heterocycles
Author(s) -
Kraft Susanne,
Hanuschek Edith,
Beckhaus Rüdiger,
Haase Detlev,
Saak Wolfgang
Publication year - 2005
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200400880
Subject(s) - chemistry , titanium , supramolecular chemistry , crystallography , metallocene , ligand (biochemistry) , cyclopentadienyl complex , acetylene , stereochemistry , crystal structure , organic chemistry , polymerization , catalysis , polymer , biochemistry , receptor
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 [Cp 2 Ti{η 2 ‐C 2 (SiMe 3 ) 2 }] ( 1 ) and [( t BuCp) 2 Ti{η 2 ‐C 2 (SiMe 3 ) 2 }] ( 2 ) as sources of titanocene fragments. Molecular rectangles can be synthesized by stepwise reduction of the titanocene dichlorides [Cp 2 TiCl 2 ] and [( t BuCp) 2 TiCl 2 ] 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.