Complex catenanes

Figure 13.19 Structure formulas of cyclophane ligand 214+, catenane ligands 224+ and 234+, and mononuclear catenane complexes.

In the case of L2" + it was not possible to synthesize [2]catenanes because the cavity of this cyclophane is too large to give stable complexes with aromatic crown ethers in the templated synthetic approach. Starting from Li" +, however, it was possible to prepare the [2]catenane ligands and L4 + which were then used to prepare several mononuclear [2]catenane complexes (Figure 23). These compounds were characterized by NMR spectroscopy, mass spectrometry and, in some cases, X-ray crystallography. 

Figure 25. Macrocyclic ligand L5, its [2]catenane derivative Ls +, and the [Ru(Me2bpy)2Ls] [2]catenane complex [54],...

A schematic representation of a catenane complex with donors from each of two interlinked rings binding to a central metal ion, and (at right) the process by which a system with differing ring components may operate as an electrochemically-driven molecular switch, involving ring rotation. 

Figure 21 Photochemically and thermally induced motions taking place in the ruthenium catenane complex 33 +. ° The representation of the decoordinated form (bottom) is only indicative and does not imply that the actual structure of the photoproduct is that shown.

Figure 25 Photoinduced rotation of the terpyridine-containing macrocyclic ring of the copper catenane complex 41 obtained by using p-nitrobenzylbromide as an electron scavenger and ascorbic acid as a chemical reductant. ...

Intramolecular mobility of metal complexes of rotaxanes and catenanes with macroheterocyclic fragments 98ACR611. 

Although the number of applications of olefin metathesis to transition metal complexes is small compared to the number of applications in organic synthesis, this field is becoming increasingly important. Spectacular examples are the double RCM reactions of copper phenanthroline complexes as a synthetic route to catenanes [113] or a recently reported approach to steric shielding of rhenium complex terminated sp-carbon chains [114]. 

When the reaction of two compounds results in a product that contains all the mass of the two compounds, the product is called an addition compound. There are several kinds. In the rest of this chapter, we will discuss addition compounds in which the molecules of the starting materials remain more or less intact and weak bonds hold two or more molecules together. We can divide them into four broad classes electron donor-acceptor complexes, complexes formed by crown ethers and similar compounds, inclusion compounds, and catenanes. 

COlfen H (2007) Bio-inspired Mineralization Using Hydrophilic Polymers. 271 1-77 Collin J-P, Heitz V, Sauvage J-P (2005) Transition-Metal-Complexed Catenanes and Rotax-anes in Motion Towards Molecular Machines. 262 29-62 Collins BE, Wright AT, Anslyn EV (2007) Combining Molecular Recognition, Optical Detection, and Chemometric Analysis. 277 181-218 Collyer SD, see Davis F (2005) 255 97-124 Commeyras A, see Pascal R (2005) 259 69-122 Coquerel G (2007) Preferential Crystallization. 269 1-51 Correia JDG, see Santos I (2005) 252 45-84 Costanzo G, see Saladino R (2005) 259 29-68 Cotarca L, see Zonta C (2007) 275 131-161 Credi A, see Balzani V (2005) 262 1-27 Crestini C, see Saladino R (2005) 259 29-68... 

Pt(en)(N03)2] and [Pt(OTf)2L2] (L = mono- or 1/2 bidentate tertiary phosphine) or dinuclear complexes of the type [Pt2(OTf)2(/i-monodentate tertiary phosphine cr-aryl = 4, -biphenyl, / -terphenyL 4,4 -benzophenone, etc.) other structural motifs employing platinum(II) have also been reported.2 0 The addition of bridging, multidentate N-donor ligands of various shapes and sizes to the labile complexes in a suitable solvent system has afforded several classes of discrete, plat-inum(II)-containing polygons, polyhedra, and catenanes. 

The group of Sauvage et al. [121] produced various [2]catenanes by using transition metal complexes as templates. Figure 41 illustrates one of their... 

Very large organogold rings (16), as well as the related dimeric [2]catenane, have been generated by the self-assembly of complex digold(I) diacetylide with a diphosphane ligand <00AG(E)3819>. 

In a recent paper, Krasnow and co-workers (120) applied a Rec A protein coating to DNA knots and catenanes to enhance visualization of the helical DNA segments and, in particular, to determine the absolute handedness of the knots. The Rec A protein is known to bind cooperatively to duplex DNA, forming a stiffened complex about 100 A in diameter in the presence of ATPase (121). 

Fe(bpe)2(NCS)2 MeOH, bpe = tra x-l,2-bis(4-pyridyl)ethene, is a supramolecular coordinationpoly-catenane, consisting of two interlocked 2D networks. Bis-pyridylethane and bis-pyiidylethene also appear elsewhere as bridging ligands in binuclear complexes (e.g., pentacyanoferrates (Seetion 5.4.2.2)). 

The iron(II) complex of the Schiff base-diimine (121) is mentioned briefly in a review more concerned with Cu" "-diimine complexes leading to helicates and catenanes—but which is also concerned with moving from tetrahedral Cu+ to octahedral metal centers as templates. 

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