Toluene complex

Gosorb Process. Like the copper—Hquor scmbbing method, the Cosorb process also reHes on the formation of a cuprous complex of carbon monoxide but uses a nonaqueous organic solvent. The preferred system uses a cuprous tetrachloroalurninate toluene complex in a toluene solvent (90). Many other organometaUic complex variants have been proposed (91—93) but have not been commercialized. 

The acidity of benzylic protons of aromatics complexed to transition-metal groups was first disclosed by Trakanosky and Card with (indane)Cr(CO)3 [61]. Other cases are known with Cr(CO)3 [62], Mn(CO)3 [63], FeCp+ [64, 65], and Fe(arene)2+ [31, 66] but none reported the isolation of deprotonated methyl-substituted complexes. We found that deprotonation of the toluene complex gives an unstable red complex which could be characterized by 13C NMR ( Ch2 = 4.86 ppm vs TMS in CD5CD3) and alkylated by CH3I [58] Eq. (13) ... 

The X-ray structure of the dibromine complex with toluene (measured at 123 K) is more complicated, and shows multiple crystallographically independent donor/acceptor moieties [68]. Most important, however, is the fact that in all cases the acceptor shows an over-the-rim location that is similar to that in the benzene complex. In both systems, the acceptor is shifted by 1.4 A from the main symmetry axis, the shortest Br C distances of 3.1 A being significantly less than the sum of the van der Waals radii of 3.55 A [20]. Furthermore, the calculated hapticity in the benzene/Br2 complex (x] = 1.52) is midway between the over-atom (rj = 1.0) and over-bond (rj = 2.0) coordination. In the toluene complex, the latter varies from rj = 1.70 to 1.86 (in four non-equivalent coordination modes) and thus lies closer to the over-bond coordination model. Moreover, the over-bond bromine is remarkably shifted toward the ortho- and para-carbons that correspond to the positions of highest electron density (and lead to the transition states for electrophilic aromatic bromination [12]). Such an experimental location of bromine is in good agreement with the results of high level theoretical... 

Noncovalent isomeric 2-butyl ion/toluene complexes. As pointed out in the previous section, key features of ion-neutral complexes, such as the mutual orientation of their components and their evolution dynamics, usually escape precise determination because of intrinsic limitations of the available experimental methodologies. This lack of information is particularly unsatisfactory since, in principle, the nature and the dynamics of an ion-neutral complex may determine its evolution to products and, thus, the reaction selectivity. Filippi and coworkers" recently... 

Two isomers were expected according to the outside or inside orientation of the thiophosphoryl group. Only one isomer was characterized showing the P=S bond directed outside. The new hemicryptophane 22 presents a molecular cavity large enough to complex a toluene molecule as shown in the solid state structure depicted in Fig. 14. The toluene complex is stabilized through Van der Waals and specific r-interactions. 

The recent isolation and structural characterization of the toluene complex of the monovalent lead cation 41 in the form of its [MeB(C6F5)3] salt is likely to trigger further theoretical work on the intriguing relationship between classical trivalent planar ER3" cations and the monovalent four-valence-electron species ER. ... 

Pauling, in one of his last scientific contributions, pointed out that, based on the observed Si—C bond length, there is a covalent silicon-carbon (of the toluene) bonding in the triethylsilicenium-toluene complex 272. The bond number, n, is 0.35, according to equation 4,... 

FIGURE 3. Ab initio optimized geometries of the [Me3Si-toluene]+ complex (4) (HF/6-31G, top) and of the [H3Si-benzene] + complex (5) [MP2(fc)/6-31G, bottom]. Values in parentheses correspond to experimental X-ray data of Et3Si+ (CgFs B- (2). Reproduced by permission of Wiley-VCH from Reference 73... 

In addition to the experimental evidence published, the reaction given in Scheme 12 is supported by the fact that -toluene complexes of Nd could be isolated, characterized and used for the initiation of diene polymerization [424]. 

By using water-soluble organic solvents, usually referred to as precipitants, the reaction can be directed to produce only one cyclodextrin. In the presence of toluene, the enzyme from B. macerans produces only (3-cyclodextrin and linear starch chains. Beta-cyclodextrin can be separated from the soluble starch chains and recovered as a precipitated toluene complex. In the presence of decanol, a-cyclodextrin is the only cyclodextrin produced using the enzyme from B. macerans.21,22 Precipitants such as large cyclic compounds similar to musk oil23 or a-naphthol and methyl ethyl ketone (butanone)24 can be used to produce 8-cyclodextrin. 

FIGURE 36. Calculated geometry [at HF/6-31G(d)] of the [Si(CFl3)3—toluene]+ complex experimental values are given in parentheses, bond lengths in pm, bond angles in deg. Adapted from Reference 470a... 

Electron depopulation of the donor and concomitant population of the acceptor in the complex results in a lowering of the vibrational frequencies in the IR spectra of the donor and acceptor moieties. Additionally, complex formation can decrease the symmetry of the donor/ acceptor dyad and can lead to increased IR intensity or the appearance of new bands. For example, in halogen/alkylbenzene complexes, the stretching frequencies of the halogens are lowered, as seen in the shift of chlorine band from 557 cm-1 in free chlorine to 530 cm-1 in the benzene complex, to 527 cm-1 in the toluene complex, and to 524 cm-1 in the p-xylene complex. Increases in the intensity of some of the arene bands are also clearly seen [23b]. 

In the Cosorb process, cuprous tetrachloroaluminate toluene complex in a toluene medium is used as the absorbing liquid instead of the copper salt so-... 

Put the sodium hydride, the p-f-butylcalix[4]arene toluene complex and the 18-crown-6 in the flask and add 650 mL of dry THF and keep the flask under a slightly positive pressure of nitrogen. 

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