Helicate bipyridyl derivatives

Other metallocycles assembled from two ligand molecules and two metal atoms have been reported by Harding et aV Bimetallic [2+2] macrocycles from the bis(bipyridyl) derivatives 3-7 and nickel(II), copper(I), silver(I), zinc(II) and cad-mium(II) have been reported. Products of this type may have either chiral, helical... 

Chiral bipyridine ligands have been explored for the asymmetric cyclopropanation of diazoacetate. For example, Lyle and Wilson reported that optically active C2-symmetric 2,2 -bipiridyl 248 served as a good ligand for asymmetric cyclopropanation in the presence of CuOTf and phenyl hydrazine (Scheme 1.116) [173]. Boyd et al. showed that a similar 2,2 -bipyridyl 249 also worked as an effective catalyst (Scheme 1.117) [174]. Mono-oxazoline-substituted 2,2 -bipyridyl derivatives 250-252 have been examined (Scheme 1.118) [175]. Chiral double helical oligopyridine... 

The Lehn group synthesised the trinuclear copper(I) complex of the substituted 2,2 -bipyridyl/ether derivative 29 and confirmed its helical structure by X-ray diffraction (Figure 6.15). A dinuclear copper(I) complex of 30 (Figure 6.15) was also synthesised and subsequently the corresponding dimeric ethane-bridged bipyridine and phenanthroline ligands were also demonstrated to yield similar di-helicate copper(I) species. These results thus indicate that helicate formation is tolerant towards minor modification of ligand structure. ... 

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