Catenanes platinum

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. 

Figure 46. Electron micrograph of a Rec-A-protein-coated catenane produced by Tn3 resol vase, shadowed at an angle of 7° with carbon platinum. The scale bar equals 1000 A (120). (Reproduced by kind permission from Nature, Vol. 304, 559. Copyright 1983 by Macmillan Journals, Ltd.)...

Catenane formation from fluorinated ligand 19 is apparently more effective than that from 12. This difference is most probably because of attractive edge-to-face or CH-jt interaction working in catenane 13, as observed in the crystal structure of platinum-incorporated catenane 14 (Figure 2). In this structure, we can observe efficient edge-to-face aromatic contacts between two phenylene units or a phenylene and a pyridine ring. 

Bauerle and coworkers have synthesized a re-conjugated catenane, utilizing Cu(I) templation and a newly developed method for acetylenic homocoupling based on the reductive elimination of platinum to generate the desired C-C bond formation (Scheme 6.16) [65,66]. The C-shaped 57 was first preorganized around Cu(I), resulting in the homoleptic bis-phenanthroline complex 58. After removal... 

Bauerle and coworkers have also prepared the catenate 3 (Chart 5.2) and characterized this species by electrospray ionization Fourier transform ion cyclotron resonance (ESI-F TlCR) mass spectrometry [32]. Reductive elimination of the platinum centers from this complex yielded a Cu+-linked conjugated catenate, which was also characterized by mass spectrometry, and the Cu could be removed with KCN to give the pure conjugated, metal-lfee catenane. The copper could not be removed from the terthiophene analogue of 3 which was prepared earlier by the same group [33]. 

Almost all metal template-based syntheses of catenanes use Cu" ", but there are a few instances of other metal ion templates, including Zn +, Pd, and Pt +. The relative substitution-lability of Pd + makes it suitable as a preparative template the substitution-inertness of Pt + has been used as the basis for a temperature-switchable catenane molecular lock [257]. This mode of switching is based on platinum-nitrogen bond dissociation at elevated temperatures. 

Self-assembly of a rigid ligand syntone 241 and its spacer-containing analog 326 with palladium and platinum(ll) ions by Scheme 4.97 afforded catenanes 630 and 631. These... 

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