Compounds of Macrocyclic Derivatives

The archetypal macrocyclic oligopyridine is cyclosexipyridine (Fig. 28). The synthesis of this molecule was achieved by Newkome and co-workers (350). The elegant synthesis reported appears to be low-yield, and, as yet, no coordination chemistry has been reported. However, 4,4 -diaryl derivatives 

The Cambridge group has recently developed the chemistry of macrocyclic ligands based upon 2,2 6, 2 -terpyridine 133, 135, 136, 139-143). The macrocycles (Figs. 29 and 30) are prepared by template condensations of 

6 -bis(hydrazino)-2,2 6, 2 -terpyridines with appropriate dicarbonyls. In general, pentagonal-bipyramidal complexes are formed (Fig. 31), in which the axial sites are occupied by solvent molecules. The electrochemistry of these compounds is of interest, and metal-centered reductions are observed. Some novel template effects, by which free ligands are obtained, have been observed in these systems. 

I should like to thank Dr. Sharon Bellard of the Cambridge Crystallographic Data Base and Dr. Paul Raithby for their invaluable assistance in obtaining structural data, and Dr. Ken Seddon for kindling and nurturing an interest in these ligands. 

Baggio-Saitovitch, E., and De Paoli, M. A., Inorg. Chim. Acta 27, 15 (1978). 

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