| Abstract
| - A nonsymmetrical [2]-catenane has been synthesized, with a 5-coordinated metal center, Zn2+, as template. A phenanthroline-based molecular chelate bearing two terminal olefins was threaded through a terpyridine-containing macrocycle and subjected to ring-closing metathesis. This new pentacoordinating catenane stabilizes strongly Zn(II), Fe(II), or Cu(II) by comparison with the analogous tetracoordinating systems.
- A nonsymmetrical [2]-catenane has been synthesized, with a 5-coordinated metal center (Zn2+) as template. Oneof the two rings contains a terdentate ligand (2,2‘,6‘,2‘ ‘-terpyridine) and the other one incorporates a bidentatechelate (1,10-phenanthroline). The first ring was prepared separately and, subsequently, Zn2+ was used as thegathering and threading element to pass the stringlike component through the ring. This open-chain species bearstwo terminal olefins, which were reacted with Grubbs first-generation catalyst (ring-closing metathesis) to afford thedesired catenane. Hydrogenation of the double bond and removal of the zinc(II) template afforded the final free[2]-catenane in 40% yield from the terdentate ligand-containing cycle and the diolefinic compound. Complexationstudies on this new pentacoordinating catenane were carried out with Fe(II) or Cu(II). The most interesting observationis that the 5-coordinated complexes obtained are strongly stabilized. Their electrochemical reduction occurs atnegative potentials.
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