Titanium cation

It was found in this work that the concentration of hydroxyl species on the surface determines the extent of Fe(C0)5 decomposition on Ti02 T e concentration of reduced titanium cations (T 3+) on the surface apparently has no effect on the process. Neither concentration affects the nature of the species formed. 

While hydrogen peroxide cannot be employed to epoxidize C,C double bonds, its combination with boron trifluoiide is effective. Accentuation of polar character (in this case an acceptor) by an external agent through complex formation achieves the activation. Similar activation [242] of hydroperoxides by vanadium and titanium cations is now well known. 

It is noted that both the micelle and the sol particles modified titanium cations are positively charged. However, the inorganic species can still condense surrounding the micelle through some pathways described by Huo et al (12). 

The increase in length of the polymer chain occurs by insertion of the monomer in a metal-carbon bond of the active complex. Dyachkovski and co-workers (149) believe, based on kinetic measurements, that the insertion takes place on a titanium cation. An ion of the type (C5H5)2Ti+—R, derived from complexing and dissociation,... 

The rate of reduction of the titanium cationic species [scheme (10)] increases when styrene is added to the system [83,90,93]. 

The active catalyst was considered to be the titanium cation arising from ionization of the Al-Ti complex ... 

The X-ray diffraction data indicates over bonding on the titanium cations, or that the shortened Ti-O bonds are under compressive stress. The neutron diffraction data, on the other hand, gives a titanium valence closer to the formal charge of 4-1-. The structure from which these bond distances were taken, presumably, should be the least strained. 

The TiOiCllO) surface facilitates both molecular and dissociative adsorption of formic acid. The dissociative adsorption of formic acid (to form surface formates) is mediated by surface oxygen anions low-energy electron diffraction studies have shown that formate is ordered into (2x1) domains with formates bridging the surface titanium cations. This ordered layer is disrupted on heating formate may recombine with surface hydroxyl groups to desorb formic acid (reverse of reaction 2) or it may decompose to form the dehydration products CO and H2O, as well as small amounts of CO2 and H2 [43]. 

The ideal (Oil -faceted surface contains exclusively five-coordinate titanium cations, so a bimolecular disproportionation reaction (see reaction (23)) to produce the ether product is precluded. Although the sputtered surface contains low-coordinate titanium cations and ample oxygen vacancies, the formation of dimethyl ether is exclusive to the (114 -faceted surface. In fact, the defect density drives all of the methoxides to fill those oxygen vacancies, and the resulting carbon is deposited on the surface, only to be burned off as CO, as illustrated in reaction (24) [74]. 

---