Group 14 amides with transition metal complexe

Another interesting and potentially very useful group of calixarene-based anion receptors is represented by systems with appended transition metal complexes of 2,2-bipyridine units. Technically, these systems utilise classical hydrogen bonding interactions of amidic/urea functions hence, from this point of view, they do not differ from many other receptors. On the other hand, the covalent attachment of bipyridine complexes of ruthenium(II) or rhe-... 

Attempts to achieve macrocycles that are capable of stabilizing highly oxidized transition metal complexes has led to the design of noninnocent ligands. The structures of high-valent chromium (V) oxo species with the two tetraamido N ligands (36) and (37) were determined. Both structures were found to contain distinctly nonplanar amide groups, and in (36) all four amides are nonplanar. 

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