Supported organo

Supported oxide catalysts were discovered at the same time (8-5) as the two-component Ziegler-Natta catalysts (6, 7) in the early 1950 s. The publications on other types of one-component catalysts [supported organo-metallic compounds of transition elements (8, 9, 9a) and titanium dichloride (10) ] appeared quite recently. 

Lindner, E Kemmler, M Mayer, H.A., and Wegner, P. (1994) Supported organo-metallic complexes. 5. Polysiloxane-bound ether-phosphines and ruthenium complexes. A characterization by solid-state NMR spectroscopy and catalysis. J. Am. Chem. Soc., 116, 348-361. 

Takashi Mono and coworkers [50] reported a silica-supported organo-chromium compound that provided catalysts that produce polyethylene with a very broad molecular weight distribution. 

Kann N. Recent applications of polymer supported organo-metallic catalysts in organic synthesis. Molecules 2010 15, 6306-6331. 

Application of the Supported Catalyst Obtained with the Use of Organo-... 

Gulea M, Masson S (2003) Recent Advances in the Chemistry of Difunctionalized Organo-Phosphorus and -Sulfur Compounds. 229 161-198 Haag R, Roller S (2004) Polymeric Supports for the Immobilisation of Catalysts. 242 1-42 Hackmann-Schlichter N,see Krause W (2000) 210 261-308 Hadjiaraoglou LP, see de Meijere A (2000) 207 149-227... 

The author is indebted to Dr. J. J. Alexander, Dr. J. P. Bibler, Dr. P. Reich-Rohrwig, and Dr. S. R. Su, his former graduate students and postdoctoral fellows, for their stimulating association with him and for their research contributions in this area of organo-metallic chemistry. Support of the research concerned with insertion reactions in the author s laboratories has been generously provided by the National Science Foundation. 

The approach comprises deposition-precipitation (DP) of Au(OH)3 onto the hydroxide surfaces of metal oxide supports from an alkaline solution of HAUCI4 [26] and grafting of organo gold complexes such as dimethyl gold (Ill)acetylacetonate (hereafter denoted as Au acac complex) [27] and Au(PPh3)(N03) [28] either in gas and liquid phase are advantageous in that a variety of metal oxides commercially available in the forms of powder, sphere, honeycomb can be used as supports. 

In the sixties of past century, a few patents issued to Bergbau Chemie [5,48,49] and to Mobil Oil [50-52], respectively described the use of CFPs as supports for catalytically active metal nanoclusters and as carriers for heterogenized metal complexes of catalytic relevance. For the latter catalysts the term hybrid phase catalysts later came into use [53,54], At that time coordination chemistry and organo-transition metal chemistry were in full development. Homogeneous transition metal catalysis was expected to grow in industrial relevance [54], but catalyst separation was generally a major problem for continuous processing. That is why the concept of hybrid catalysis became very popular in a short time [55]. 

Structures of immobilized rhodium complexes on the sihca support have been proposed on the basis of the data obtained from C, P and Si MAS-NMR. NMR spectra of the rhodium-modified solid materials confirmed that trimethylsiloxide ligand was removed from the rhodium coordination sphere during the immobilization process. Formation of a new covalent bond between the rhodium organo-metallic moiety and the silica support occurs, probably with evolution of trimethylsilanol, which is rapidly converted into disiloxane (Me3Si)20. The presence of this molecule in the solution obtained after the silica surface modification process was confirmed by GCMS analysis. 

Since grafting stabilizes species that would be too reactive in solution (in general, by allowing for isolated sites), and supported species may present catalytic properties unknown to the molecular chemistry, a lack of data concerning d(0) metal complexes derived from Nb and Cr is astonishing. Hopefully, the knowledge accumulated so far will be an incentive to develop the surface organo-metallic chemistry of these elements as well as the surface chemistry of the rare earths. 

Treatment of the enantiomerically enriched acyclic allylic carbonate (S)-l (97% ee) under the standard reaction conditions furnished the allylic alkylation product (S)-14 (95% ee) in 86% yield, with net retention of absolute configuration (Eq. 3). This result implies that the displacement occurs via a classical double inversion process, albeit through a configurationally stable distorted u-allyl or enyl ff+n) organorhodium intermediate. This is supported by the fact that the achiral ff-spedes iii would undoubtedly have afforded the racemate of 14 (Scheme 10.3). Additionally, the enyl (a+n) organo-metallic intermediate provides a model for the regio- and enantiospedfidty observed in the reaction. 

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