Ethylene complexes table

The IR spectra of many hydrocarbon ligands on metal surfaces also resemble those of discrete organometalUe species, as shown by the example of ethylene complexes (Table 5-7). Weakening of the double bond is evident both in the supported catalyst and in the isolated complex (for eomparison gaseous ethylene has an IR band at 1640 cm ). 

These considerations do not involve Ag(I) and Cu(I) complexes with olefins containing both electron-accepting and electron-donating substituents such complexes are less stable compared to the ethylene complex (Table 6.11). 

Figure 4.79 displays the optimized structures of secondary-Cp (IIsec) and primary-Cp(IIPri) complexes, and Table 4.43 includes geometrical and charge parameters of these propylene complexes for comparison with those of the corresponding ethylene complex in Table 4.42. The IIsec complex can be seen to have smaller Ti—Cp metal-alkene separation (by 0.1 A) and other evidence of tighter metal-alkene binding than that in the IIpri complex, in accordance with the donor-acceptor stabilizations discussed above. 

The treatment of the UPS of the tr-allyl complex (CsHs)2Nb(C3Hs) is similar to that of the ethylene complexes. One significant difference between the ethylene and tr-allyl complexes, however, is that the symmetry is reduced to C2 in the latter. The correlations between the appropriate orbital symmetries in the C2v and Cs point groups are indicated in Table XIV. 

Further characterization of the ozone—mesitylphenylethylene complex produced at —150 °C was done by NMR and visible spectral studies. The low temperature NMR spectra of the starting olefin, the red complex (ozonized olefin at —150°C) and the dilute reaction mixture at —135°C containing the epoxide of 1-mesityl-1-phenylethylene are described in Table III. The —150 °C solutions of the olefin and the complex contain the same bands, the only difference being that the peaks were shifted slightly upfield in the formation of the complex. Such is typical of tt complexes with very little charge transfer, such as iodine and tetracyano-ethylene complexes of various aromatic molecules (5, 6). When the temperature of the ozonized reaction mixture was allowed to rise above about —145 °C, the NMR spectrum changed, giving rise to the characteristic peaks of the epoxide of 1-mesityl-l-phenylethylene. 

The zirconocene complex 11, when activated with methylalumoxane, shows high activity in ethylene polymerization (Table 9) which is slightly larger than... 

Some of these oxygen-bridged heterobimetallic compounds were found highly active as catalysts in ethylene polymerization. Tables 1-3 represent the results of ethylene polymerization experiments. All polymerization reactions were carried out under extremely mild conditions at room temperature and at ambient pressure. The data of Tables 1-3 show that the highest activities (activities of the order of 10 g-(mol of catalyst) h ) in ethylene polymerization were observed for the complexes of the type [LAlMe(g-0)MRCp2] (12a, 13, and 15, Scheme 9) (27,45). These catalysts exhibited activities in ethylene polymerization two orders... 

TABLE I Infrared Data of L2Pd-Ethylene Complexes ... 

Another TM-catalyzed reaction that has been studied at the DFT and ab initio levels of theory is the epoxidation of ethylene with rhenium peroxo complexes. Table 17 shows calculated reaction energies at the MP2, B3LYP, and CCSD(T) levels of theory using basis set II (84). 

Table V. Kinetic and Thermodynamic Optical Yield of trans-(N,//)-[PtCl(L-am)(olefin)] on the Reaction of the Corresponding Ethylene Complexes with Olefins (22)...

Temkin and co-workers have investigated the thermodynamic properties of the soluble complexes of unsaturated hydrocarbons with various metal salts with particular reference to their role in catalytic reactions. Using a potentio-metric technique, they were able to calculate the thermodynamic data shown in Table 6 for the silver(I)-acetylene complexes 30) and the silver(I)-ethylene complex 31). The results obtained for acetylene have been related to the low activity of silver salts as catalysts for the hydration of acetylene. For the sil-ver(I)-ethylene complex, the relationship between the ionic concentrations and... 

Microscale (matrix isolated only) metal atom-olefin codepositions yield unstable TT-olefin-metal complexes that can be investigated by matrix isolation spectroscopy. By varying the concentrations of alkene and metal in the inert gas (at 10-50K), mono-, bisand tris-olefin-metal complexes can be observed. Table 1 lists ethylene and tetrafluoro-ethylene complexes prepared for Co, Ni and P(ji-3.io.ii.i2 nd If the... 

Computed olefin complexation energies for a number of ethylene complexes are collected in Table 1.43 46 47,61 68 j gre are clear differences in binding energy as a function of theoretical method it appears as though the major variation is due to the inclusion of electron correlation. Compare entries 32 and 34 with entries 33 and 35—38. Density functional theory (DFT) and correlated wave function approaches give similar results compare entry 30 with entries 35—... 

---