Ethylene clusters

Method (i), the thermal or photolytic ejection of CO, is known to be unfavorable (see above). Method (ii), the removal of CO as C02 by oxidation with Me3NO, is an easily carried-out procedure and has led to the synthesis of many hitherto inaccessible compounds. By this route the ethylene cluster Os3(CO)nC2H4 has been synthesized. 

The structures and isomerization of C4Hg+ ions in connection with the problem of ethylene clusters has been the subject of many studies. Doepker and Ausloos192 studied the photolysis of cyclobutane, its deuterated isotopomer and mixtures thereof, and in their detailed product analysis they found cA-2-butene, trans-2-butene and 1-butene as major ionic products in the approximate ratio of 1 1 2. Lias and Ausloos193 determined... 

The ethylene cluster experiments and interpretation are discussed below as follows. Section II summarizes important aspects of the experiment. Section III gives details on the spectral analysis with respect to inhomogeneous versus homogenous broadening as well as saturation effects. Section IV discusses structural information obtained from the spectra. Section V discusses the vibrational predissociation mechanism for these complexes and compares the results to other systems. 

Ethylene cluster complexes with /13-ethylidyne ligands... 

M. P. Casassa, D. S. Bomse, J. L. Beauchamp, and K. C. Janda, Infrared photochemistry of ethylene clusters, J. Chem. Phys. 

Ethylene—Dicarboxylic Acid Copolymers. Partial neutralization of copolymers containing carboxyls in pairs on adjacent carbons, eg, ethylene—maleic acid, has been described (11). Surprisingly, there is no increase in stiffness related to neutralization. Salts with divalent metal cations are not melt processible. The close spacing of the paired carboxyl groups has resulted in ionic cluster morphology which is distinct from that of the commercial ionomer family. 

There are many related compounds, including rhodium carbonyl cluster anions, which are present in the solutions cataly2ing ethylene glycol formation and which may be the catalyticaHy active species or in equiUbrium with them (38). 

A few industrial catalysts have simple compositions, but the typical catalyst is a complex composite made up of several components, illustrated schematically in Figure 9 by a catalyst for ethylene oxidation. Often it consists largely of a porous support or carrier, with the catalyticaHy active components dispersed on the support surface. For example, petroleum refining catalysts used for reforming of naphtha have about 1 wt% Pt and Re on the surface of a transition alumina such as y-Al203 that has a surface area of several hundred square meters per gram. The expensive metal is dispersed as minute particles or clusters so that a large fraction of the atoms are exposed at the surface and accessible to reactants (see Catalysts, supported). 

Detailed measurements of the solubility between the lower and upper critical end points have been made only for the solutions in ethylene of naphthalene,14 hexachlorethane,30 and />-iodochloro-benzene.21 Atack and Schneider2 have used dilute solutions of the last-named substance to study the formation of clusters near the gas-liquid critical point of ethane. 

A wide range of ethylene complexes, both mononuclear and higher cluster in nature, have been synthesized, and studied, by the metal atom-matrix technique. In this Section, we shall focus on the reactions... 

In the presence of the product ethylene during turnover the MoFe protein exhibits an EPR signal, with g values at 2.12, 1.998, and 1.987 129), which has been demonstrated to arise from FeMoco in an S = z spin state 130). However, direct interaction of the ethylene with the metal-sulfur cluster was not demonstrated. 

FIGURE 13.4 Schematic representation of maleic anhydride graft-rich clusters in maleated ethylene-propylene copolymers (EPMs). 

FIGURE 22.12 Uniaxial stress-strain cycles of ethylene-propylene-diene monomer (EPDM) samples with 60 phr silica at different prestrains = 10%, 20%, 30%, 40%, and 50% (symbols) and fittings (lines) with the stress-softening model Equations 22.19-22.24. The fitting parameters are indicated. The assumed cluster-size distribution is also shown, which differs from the one in Equation 22.24. (From Kliippel, M. and Heinrich, G., Kautschuk, Gummi, Kunststojfe, 58, 217, 2005. With permission.)... 

The fact that only ethylene and tetramethylethylene are evolved from exp-[8]rotane 168 and permethyl-exp-[6]rotane 173 upon thermal decomposition leads to the conclusion that the spirocyclopropane moieties in these expanded [n]rotanes fragment only externally and leave carbene moieties behind. Indeed, the MALDI-TOF mass spectra of several exp-[ ]rotanes show fragment ions with M minus 28. Thus, if this fragmentation in an exp-[n]rotane were to continue n times, a cyclic C carbon cluster would be left over. So far, however, a fragment ion with m/z = 480 corresponding to 182 has not been recorded in the mass spectrum of exp-[8]rotane 168 and it remains to be seen whether a Cgo cluster 183 will be detected in the mass spectrum of exp-[12]rotane 171 (Scheme 35). 

By dynamic light scattering it was found that, in surfactant stabilized dispersions of nonaqueous polar solvents (glycerol, ethylene glycol, formamide) in iso-octane, the interactions between reversed micelles are more attractive than the ones observed in w/o microemulsions, Evidence of intermicellar clusters was obtained in all of these systems [262], Attractive intermicellar interactions become larger by increasing the urea concentration in water/AOT/ -hexane microemulsions at/ = 10 [263],... 

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