Bipyridine complex structures

M. Gottschaldt, D. Koth, D. Muller, I. Klette, S. Rau, H. Gorls, B. Schafer, R. P. Baum, and S. Yano, Synthesis and structure of novel sugar-substituted bipyridine complexes of rhenium and 99m-technetium, Chem. Eur. 13 (2007) 10273-10280. 

Their activity compared to those of the Cu(II)-terpyridine and Cu(II)-bipyridine complexes indicate notable cooperativity between the metal centers (k mJ2 kmanoaet = 18-26 at pH = 7 and ca. 10 at the pH optimum of the given complex). The pH-rate profile of both complexes shows a bell-shaped structure. Thus, the postulated double general-base catalysis for both complexes is not fully justified. In case of 38 this was explained by possible inhibition by the buffer used. While double Lewis-acid activation is proposed for 37, single Lewis-acid activation is favored for 38. 

Mdssbauer spectra of bonding and structure in, 15 184-187 reactions with diborane, 16 213 stabilization of, 5 17, 18-19 cyanates, 17 297, 298 cyanide complexes of, 8 143-144 cyclometallated bipyridine complex, 30 76 diazene complexes, 27 231-232 dinitrogen complexes, 27 215, 217 diphosphine complexes of, 14 208-219 dithiocarbamates, 23 253-254 -1,2-dithiolene complexes, 22 323-327 hydrogen bonding, 22 327 halide complexes with phosphine, etc., 6 25 hexaflouride, structure, 27 104 hydride complexes, 20 235, 248-281, see also Transition metal-hydride complexes... 

To learn more about the effect of the metal ion on the binding of these receptors we also synthesized a covalently linked analog of the [Mll2]+ complex in which the central metal bis(bipyridine) complex was substituted by a spirobifluorene moiety [6], Figure 2.1.10 shows the structures of both, which we obtained from molecular modeling studies. 

A poorly characterized, insoluble, gray-black 2,2 -bipyridine complex formulated as [ReCl3-(bipy) 3/2H20] (the value of n is unknown) has been obtained from the reaction of (BuJN)2Re2Cls with bipy in n-butanol. It is paramagnetic (jt = 1.36 BM), but its spectral properties give few clues as to its structure.108... 

With complete exclusion of air, fra i -[FeCl2(H20)4] reacts with acetylacetone to form hydrated bis(2,4-pentanedionato)iron(II). The complex is coordinatively unsaturated and forms an interesting tetrameric structure [Fe4(acac)g] in which two asymmetric triply oxygen bridged dimers (32) are linked by rather long Fe-C bonds (2.785 A, 33). [Fe(acac)2] forms simple hexacoordinate adducts in reaction with a variety of bases, for example, heterocyclic diimines snch as bipyridines. Complexes formed by iron(II) with other /3-diketonates are polymeric and highly air sensitive. Iron(III), however, forms a series of stable highly colored... 

Cluster [Ru5C(CO)i5] reacts with 2,2 -bipyridine and 1,10-phenanthroline in the presence of McaNO to yield the major monosubstitution products 38 and the orthometalated complexes 39 in minor amount (both structures illustrate the 2,2 -bipyridine complexes) (97JCS(D)2705). 

As shown in Scheme 11.Id, these polymers consist of the main backbone of (i) a nonconductive polymer (25-27), or a polymeric ionomer (29) or (ii) a backbone of an ECP (28) to which pendant, localized redox-centers, such as ferrocene (Fc), bipyridine-complexes of Ru, Os, and so forth, or even low-molecular-weight thiophene oligomers, are covalently attached (25, 27, and 26, respectively). Covalent attachment is characteristic of the structure 28, whereas 29 contains a typical electrostatic bond between the electroactive bipyridine-complex of Ru and the polymeric ionomer s backbone. 

Metal-directed self-assembly has recently been the subject of explosive development which has made possible the synthesis of many fascinating and complex structures [1]. By combining building blocks derived from various families of molecules and metal ions, the structure of the resulting multicomponent systems can, in principle, be varied infinitely at will. Early examples involve simple linear bridging ligands with two linking sites, such as 4,4 -bipyridine and aromatic dicyanide or dicarboxylic acids, as summarized in Table 1 [2-7]. 

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