Catenand complexes

Fig. 6.1 Synthesis of a cuprocatenane. High dilution conditions for the second step allow the in-tremolecular condensation of the terminal OH groups on a single phenanthroline. Removal of the metal from the copper(I) complex by treatment with Me4N + CN in acetonitrile/water affords the catenand. Reproduced with permission from C. O. D. Buchecker, J.-P. Sauvage and J.-M. Kern, J. Amer. Chem. Soc. 106, 3043 (1984). (1984) American Chemical Society.

Scheme 18. Synthesis of the oligo[2]catenands 52 (i) 4-(di-methylamino)pyridine-p- tolu-enesulfonic acid 1 1 complex plus /V,/V -diisopropylcarbodi-imide.

Scheme 19. Synthesis of the poly[2]catenand 51b via demetalation of the poly[2]catenate 51a (i) 4-(dimethylamino)pyridine-p-toluenesulfonic acid 1 1 complex plus AT V -diisopro-pylcarbodiimide (ii) KCN, THF.

The catenands are synthesized using the metal ion template effect, whereby a bis complex is formed from an a,a -disubstituted o-phenanthroline. This initial product is treated with a diiodoal-kane to effect the ring closures.34... 

Two interlocked macrocyclic ligands as in (15) are topologically related to the catenanes, whence the name catenand derives.34,186 187 These macrocycles complex a variety of metals, presumably in a tetrahedral geometry.34,186 The stabilizing effect of the catenand topology is evident in the observed redox stability of the nickel(I) complex186 as well as the reluctance toward demetallation, observed for the copper(I) complexes.187... 

Inorganic templating and self-assembly provide coordination compounds whose geometries make possible the synthesis of complex structures, namely of cyclic multiporphyrin arrays [9.13a, 9.179], of inorganic rotaxanes [9.97a, 9.180], of multi-catenates and catenands (see 181) [8.281, 8.282] and even of molecular knots (see 182) [8.282, 9.77, 9.181] (in 181 and 182 a) with, b) without Cu(l) template). 

When the copper complex of 7.62 reacts with ICH2(CH2OCH2)4CH2l in the presence of base, an intramolecular cyclisation occurs to form the macrocyclic ether 7.63. However, because of the arrangement of the starting ligands about the copper(i) centre, the two macrocycles are interlinked, and the consequence is the formation of the copper(i) complex of the catenand (catenand = catenane ligand) (Fig. 7-41). 

These complexes of catenands are remarkably stable. However, treatment of the complex with cyanide results in demetallation and the formation of the free catenane, in which the two macrocyclic ligands are still interlocked. There is a conformational change upon demetallation and in the solid state the rings have slipped . It is not trivial to estab-... 

The free catenand 27 was easily obtained from 26f4 by removing the metal with KCN. Interestingly, remetallation of 27 by the divalent copper salt Cu(BF4)2 afforded the hexacoordinate species 26(6)2+ (see Figure 21) as a very pale green complex (A.max = 687 nm e = 100 mol-1 L cm-1). 

Cesario, M., Dietrich-Buchecker, C.O., Gui Them, J., Pascard, C. and Sauvage, J.P. 1985. Molecular structure of a catenand and its copper (I) catenate complete rearrangement of the interlocked macrocyclic ligands by complexation, J. Chem. Soc. Chem. Commun., 244-247. 

Catenands (17) are interlocked macrocyclic ligands, which complex a variety of metal ions. ... 

CU.10+ is made of a catenand (metal-free) and a catenate (metal-complexed) moiety. Selective excitation of the Cu -complexed moiety in the visible spectral re-... 

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