Organometallic complexes, transition metal

Slcreospecific solution polymerization has been emphasized since the discovery of the complex coordination catalyses that yield polymers or butadiene and isoprene having highly ordered microstructures. The catalysts used are usually mixtures of organometallic and transition metal compounds. An example of one of these polymers is cis- 1.4-polybutadiene. 

Varghese V, Saha M, Nicholas KM (1988) Org Synth 67 141 Nicholas KM (1987) Acc Chem Res 20 207 Caffyn AJM, Nicholas KM (1995) Transition metal alkyne complexes transition metal stabilized propargyl system. In Abel EW, Stone FGA, Wilkinson G (eds) Comprehensive organometallic chemistry II, vol 12. Pergamon Press, Oxford, p 685 Schreiber SL, Klimas MT, Sammakia T (1987) J Am Chem Soc 109 5749 Nakamura T, Matsui T, Ta-nino K, Kuwajima I (1997) J Org Chem 62 3032... 

In conclusion, we have shown that attachment of transition metal complexes to polymer supported triphenylphosphine leads to air stable, versatile immobilised catalysts that are as active as their homogeneous analogues and have the advantage that they can be re-used numerous times. Work is currently underway to exploit the activity of other polymer-supported organometallic complexes in metal-mediated organic synthesis. 

Nicholas, K. M., Caffyn, A. J. M. Transition metal alkyne complexes Transition metal-stabilized propargyl systems, in Comprehensive Organometallic Chemistry II. (eds. Abel, E. W., Stone, F. G. A.,Wilkinson, F.), 12, 685-702 (Oxford, 1995). 

New Applications of TCNE in Organometallic Chemistry, A. J. Fatiadi (1987). Selected reactions used in organometallic synthesis are reviewed. 311 references are given. Structure and bonding of metal-TCNE complexes as well as reactions of TCNE with main-group organometallics, with transition-metal complexes, with metal-coordinated alkenes and alkynes, and reactions of platinum-family complexes are discussed. 

Farina, V., in Abel, E.W., Stone, F.G.A., Wilkinson, G., Hegedus, L.S., Eds.,Transition Metal Alkyl Complexes Transition Metal Alkyl Complexes Oxidative Addition and Transmetallation in Comprehensive Organometallic Chemistry II, Vol. 12, Pergamon, Oxford, 1995, p. 161. 

As described above, mesoporous materials can be used as supports for metals, oxides, acids, and bases. However, perhaps the most intriguing and exciting application is in catalysis involving large active molecules such as organometallics and transition metal complexes immobilized within the pores, as illustrated in Fig. 12. The large surface areas of mesoporous materials makes the materials very attractive as supports for such active phases. 

Gansow, O. A., Vernon, W. D., Carbon-13 Nuclear Magnetic Resonance Studies of Organometallic and Transition Metal Complex Compounds, Top. Carbon-13 NMR Spectrosc. 2 [1976] 269/341. 

Grothahn, D.B. (1995) Transition metal alkyne complexes transition metal catalyzed cyclotrimerization, in Comprehensive Organometallic Chemistry II, vol. 12 (eds. E.W. Abel, F.G.A. Stone, G. Wilkinson, and L.S. Hegedus), Pergamon, Oxford, pp. 741-770. 

Ziegler catalysts Complex catalysts prepared by interaction between an organometallic derivative and a transition metal derivative. A typical catalyst is the product of the interaction of TiCU and AIBU3. These catalysts polymerize olefins, particularly ethylene, to polyolefins, the polymerization generally being in a siereoregular manner. 

Mashima K, Nakayama Y and Nakamura A 1997 Recent trends in polymerization of a-olefins catalyzed by organometallic complexes of early transition metals Adv. Polym. Sc/. 133 1-54... 

A large number of organometallic compounds are based on transition metals Examples include organic derivatives of iron nickel chromium platinum and rhodium Many important industrial processes are catalyzed by transition metals or their complexes Before we look at these processes a few words about the structures of transition metal complexes are m order... 

Organometallic chemistry (see p. 1199) is not particularly extensive even though gold alkyls were amongst the first organo-transition metal compounds to be prepared. Those of Au are the most stable in this group, while Cu and Ag (but not Au ) form complexes, of lower stability, with unsaturated hydrocarbons. 

The first ri -transition metal organometallic complexes 272 were made from Li(Mc4C4ESiMe3) (E = Si, Ge) and Cp HfC (98JA8245). Species 272 (E = Si) with trimethylphosphine forms the Hf-PMc3-adduct. 

B. Non-Metal and Non-Transition Metal Organometallic Complexes of Imidazoles. 120... 

In comparison with catalytic reactions in compressed CO2 alone, many transition metal complexes are much more soluble in ionic liquids without the need for special ligands. Moreover, the ionic liquid catalyst phase provides the potential to activate and tune the organometallic catalyst. Furthermore, product separation from the catalyst is now possible without exposure of the catalyst to changes of temperature, pressure, or substrate concentration. 

Ziegler-Natta catalysts-—there are many different formulations—are organometallic transition-metal complexes prepared by treatment of an alkyl-aluminum with a titanium compound. Triethylaluminum and titanium tetrachloride form a typical preparation. 

In essence the active centers for catalytic polymerization of olefins are organometallic complexes of transition metals. For this reason a search for individual organometallic compounds that would possess catalytic activity in olefin polymerization is of great interest. The first attempts to use organometallic compounds of transition metals as catalysts for olefin polymerization were made long ago [e.g. CH3TiCl3 as a catalyst for polymerization of ethylene 116). However, only in recent years as a result of the application of relatively stable organometallic compounds of transition... 

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