Characterization crystal structure analysis

The (EDT-TTF-I)2Br salt described above [36] and the 1 1 (TTFI4)I salt reported by Gompper [51] were the only structurally characterized salts with simple halide anions until Imakubo recently described an extensive series of Cl" and Br" salts from several ortho-diiodo tetrathiafulvalene, tetraselena-fulvalene and dithiadiselenafulvalene derivatives (Scheme 8) [62], The X-ray crystal structure analysis of the nine salts described there show a variety of halogen bonded motifs, demonstrating the adaptability of the supramolecu-lar interactions to other structural requirements imposed by the nature of the heteroatoms (O, S, Se) in the TTF frame. Indeed, in (EDT-TTF-l2)2X-(H20)2 (X = Cl, Br), a bimolecular motif (Fig. 6) associates two partially oxidized EDT-TTF-I2 molecules with one Br" anion and one water molecule. 

The first transition metal isonitrilate complex reported was the tetrahedral Co-1 complex [Co(C=NPh )4] where Ph = 2,6-Me2C6H3,96 characterized by a crystal structure analysis. Oxidation yields the zerovalent dimer Co2(C=NPh )8, which features two bridging isonitrile groups. 

Insertion and rearrangement steps were also observed in the reaction of 1 with B2C1443 (Scheme 14). Compounds 52 and 53 were characterized by NMR spectroscopic or mass-spectrometric data, compound 54 by an X-ray crystal structure analysis. 54 may be regarded as a borane-stabilized boranediyl, consisting of a Me5C5B nido-cluster unit (Fig. 8). 

Thus, if information is being sought about intermediates for this type of catalysis, it does not make sense to analyze systems that lead to first-order reactions Rather, systems in which the hydrogenation rate is independent of the substrate concentration would be more appropriate. Indeed, for both catalytic systems shown in Figure 10.21, in each case one of the catalyst-substrate complexes could be isolated and characterized by crystal structure analysis (Fig. 10.23). 

The 11-vertex /0-diphosphaborane [7,9-Ph2- ri/ -7,9-P2B9H9] 35 was synthesized in 20% yield from [B9H12] and PhPCl2 and was characterized by NMR spectroscopy and X-ray crystal structure analysis.141... 

Dorset, D. L. and Moss, B., Electron crystal structure analysis of linear polymers - an appraisal, in Polymer Characterization, Carver, C. D. (Ed.), Advances in Chemistry Series, Vol. 203, American Chemical Society, Washington, DC, 1983, 409-416. 

Stable complexes of titanium, 281 [157], cobalt, 282 [157], and platinum, 283, with a bicyclopropylidene ligand [158] have been obtained (Fig. 7), showing that 1 is a remarkably good ligand in spite of being a tetrasubstituted alkene. The complex 282 has been fully characterized by an X-ray crystal structure analysis [157]. 

From the encouraging results obtained in the reactions of a series of gold(III) oxo complexes with olefins [56], Cinellu et al. tried to achieve the supposed oxametalla-cyclic intermediate, which had never been isolated before [25]. In the reaction of 8 and norbornene 56, if the - atoms were considered to be equivalents of coordinated water, and it was therefore possible to talk about the gold-catalyzed addition of water to an alkene. The metallaoxetane 58 was separated from the gold-alkene complex 57 and characterized by X-ray crystal structure analysis. The subsequent stoichiometric reaction yielded epoxide 59 (Scheme 8.5). 

The first W—W quadruply bonded complexes characterized were [W2Me Cl8 ]4- prepared by treatment of WC14 with methyllithium. Crystal structure analysis has established the short W—W distances of 2.264 and 2.263 A for the methyl and the mixed chloromethyl derivatives respectively. In addition, these compounds have the expected eclipsed stereochemistry.327,328... 

In a series of papers, Takekuma and co-workers374-377 have reported the synthesis of a variety of 3-guaiazulenylmethyl cations 159 [Eq. (3.44)] with full spectroscopic characterization (UV-visible, IR, multinuclear NMR) and X-ray crystal structure analysis. The corresponding 2-furyl-, 2-thienyl-, and 2-pyrrolyl-substituted... 

Fluorination of (C6F5)2S with XeF+ has been applied to obtain (C6F5)2FS+MF6 (M = As, Sb) salts.224 An S—Fbond distance of 1.584 A was found by crystal structure analysis of (C6F5)2FS+SbF6. Minkwitz et al 225,226 have reported the synthesis and structural characterization of the cyclic monofluorinated cations 81 and 82. The S— F bond lengths (1.51 and 1.522 A) are significantly shorter than that in (C6F5)2FS+ (1.584 A). 

The unstable bright yellow crystals of 577-benzo /]-l,2,3,4-tetrathiepine-l-oxide 26 (Section 13.17.5.3) were characterized by an X-ray diffraction study <1996ZN1511>. The X-ray crystal structural analysis of bis-tetrathiepinyliden 6 (Figure 11) showed that it possesses C, symmetry with a central exocyclic CC double bond similar to tetrathiaful-valences <1995CB561>. 

By replacing the natural substrate homoprotocatechuate (3,4-dihydroxyphenyl acetate) with the slower reacting substrate analog 4-nitrocatechol, six intermediates of the catalytic reaction cycle of 2,3-HPCD could be observed experimentally, four of which could even be characterized by X-ray crystal structure analysis [22], Scheme 2.4 gives an overview of the proposed reaction mechanism. 

Furthermore, as shown in Figure 3.9, Nicholas and coworkers isolated azodioxide complex 37 as a reactive intermediate, which could be characterized by X-ray crystal structure analysis [132, 133], Isotope labeling studies established complex 37 to be indeed the catalytically active species. 

Related classes of gitonic superelectrophiles are the previously mentioned protoacetyl dications and activated acyl cationic electrophiles. The acyl cations themselves have been extensively studied by theoretical and experimental methods,22 as they are intermediates in many Friedel-Crafts reactions. Several types of acyl cations have been directly observed by spectroscopic methods and even were characterized by X-ray crystal structure analysis. Acyl cations are relative weak electrophiles as they are effectively stabilized by resonance. They are capable of reacting with aromatics such as benzene and activated arenes, but do not generally react with weaker nucleophiles such as deactivated arenes or saturated alkanes. 

The complex between ( )-37 and KPF6 was characterized by X-ray crystal-structure analysis, which confirmed the close tangential orientation of the ionophore moiety with respect to the fullerene surface, which had been predicted by computer modeling (Figure 15). 

Ethylene-W -diacctic acid (EDDA) and similar ligands form well-characterized octahedral complexes in aqueous solution where C-13 coordination-induced chemical shifts, 51V and nO NMR spectroscopy has been utilized in their study [40], X-ray crystal structure analysis showed formation of the (3-cis isomer, whereas NMR studies clearly showed two complexes in solution. The nO NMR studies [40] were fully consistent with retention of octahedral coordination by both of the isomers, and these two compounds were assigned as the a- and p-cis isomers, which are depicted in Scheme 4.11. The study of these isomers in water (a-cis, -514 ppm 13-... 

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