Cationic Organometallic Complexes

The reaction of silica-supported bis(allyl)Rh complexes with PMe3 followed by hydrogen treatment leads to the synthesis of the surface SiO-RhH2(PMe3)4+ as the first example of a cationic organometallic complex attached to the silica surface by ion pairing. The counterion is presumed to be a siloxy group SiO- on the silica surface.276 277... 

Scheme 11). Alternatively the quaternary salts can be converted thermally into acyliron chelate complexes which can then be oxidized to azetidinones (Scheme 12). Extension of the method to the synthesis of a condensed azetidinone is illustrated in Scheme 13, but the scope of the procedure has not been evaluated. It will also be of interest to assess the utility of other cationic organometallic complexes preliminary studies have shown that molybdenum complexes behave in an analogous manner but the oxidative cyclization is inefficient (Scheme 14). 

Zeimentz, P.M., Arndt, S., Elvidge, B.R. etal. (2006) Cationic organometallic complexes of scandium, yttrium, and the lanthanoids. Chemical Reviews, 106, 2404. 

Hydride-ion reactions with the ligands of some cationic organometallic complexes results in C—H bond formation, e.g. ... 

A relatively new development in the field of carbocationic polymerization reactions, and the primary focus of this contribution, follows the realization, only a few years ago, that a few cationic organometallic complexes which behave as excellent Ziegler—Natta catalysts for some monomers can also behave as... 

As presented in the previous section, the chiral self-assembled M4L6 supramolecular tetrahedron can encapsulate a variety of tetra-alkyl ammonium guests and presents high configurational stability. Raymond, Bergman and coworkers, used the tetrahedral [Ga4(23)6] (5.32) (H4(23) = l,5-bis(2,3-dihydroxybenzamido)naphthalene) (Figure 5.11) as a host to encapsulate reactive cationic organometallic complexes and studied some catalytic transformations within the chiral environment of the cavity of the supramolecular tetrahedron. 

Category A solidification by metal and alkylammonium cations, B solidification by polycations, C solidification by cationic organometallic complexes, D immobilization by wet impregnation, E immobilization by solvent-anchoring and covalent linkage, F immobilization by anion-exchange. 

The cationic organometallic complexes containing a CH3, NH2 or OH in p position with respect to the metal can be easily deprotonated ... 

Other Reactions. Trityl fluoroborate has been used often to prepare cationic organometallic complexes, as in the conversion of dienyl complexes of iron, ruthenium, and osmium into their cationic derivatives. It alkylates pyridines on the nitrogen atom in a preparation of dihydropyridines and acts as a tritylating agent. It has also been used in attempts to form silyl cations and silyl fluorides from silanes. Finally, it has been reported to be a usefiil desiccant. ... 

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