Organometallic tt complexes

The constituents are arranged in an alternating way, Mes/Cr/Mes/Cr/Mes. In general, liquid phase addition reactions occur at a metal site, pre-formed in a support medium that contains arene functionalities (48). Free arene substituents and organometallic tt-complexes can therefore trap a diffusing metal atom. Under well-defined conditions, such reactions are favored over competing metal atom polymerizations. 

The first organometallic tt complex of vitamin A acetate, (75) (R = CH2OCOCH3), obtained by reaction of the acetate with Fe3(CO)i2... 

In several recent communications (1-4) we have reported preliminary results of our attempts at the synthesis of organometallic tt -complexes of the pentalene system. The key step involved solvolysis, in acid solution, of the alcohols l, 3 and 5 to obtain the metal it -complexes of the pentalenylium, methylpentalenylium and benzopentalenylium cations, 2, 4 and 6 respectively. 

Some of the most interesting structural studies in 2010 were on Group 2 organometallics tt-complex. Developments in the chemistry of Mg-Mg bonded, Mg compound [ N(Dipp) C(Me) 2CH MgMg N(Dipp) C(Me) 2CH ] (16) are particularly noteworthy. 16 reduces benzophenone and anthracene to give thermally-stable magnesium ketyl and magnesium anthracene complexes, 17 and 18 respectively (Scheme 5). ... 

Asymmetric Synthesis by Homogeneous Catalysis Carbonyl Complexes of the Transition Metals Hydride Complexes of the Transition Metals Organic Synthesis using Transition Metal Complexes Containing tt-Bonded Ligands Polynuclear Organometallic Cluster Complexes. 

A variety of organometallic, ir complexes are now known, in which both TT-cyclopentadienyl and ir-cycloheptatrienyl ligands are bonded simultaneously to the same transition metal, providing a series of unique mixed sandwich complexes. The first of these, x-cyclopentadienyl-x-cyclo-heptatrienyl-vanadium (XXXI), was described by King and Stone (153)... 

M. Bochmann, Organometallics 1 Complexes with Transition Metal-Carbon (7-Bonds. Oxford Univ. Press, Oxford, 1994 M. Bochmann, Organometallics 2 Complexes with Transition Metal-Carbon tt-Bonds. Oxford Univ. Press, Oxford, 1994. 

TT Beer, P. D., Hayes, E. J., Transition metal and organometallic anion complexation agents . Coord. Chem. Rev. 

As for the tt complexes, there are additional a adducts that are only partially characterized. The multiple addition analogues Cgg S2Fe2 (CO)g (n = 2-3) (53) are known, and Wudl prepared Cgo(H)(Li) by reaction of Cgg with LiBHEtg (56). An organometallic radical, CggAg, was prepared and analyzed using matrix isolation and ESR techniques (57). 

The TT-complexation of the aromatic ring with transition metal organometallic moieties induces major changes of properties such as solubility, acidity, and host-guest activity. 

The TT-complexation of an arene to iron facilitates nucleophilic reactions. Astruc and co-workers have made use of this to prepare a spectacular array of new organometallic and organic compounds. For example,the reaction of [Fe(C6Me6)Cp][PF6] with Bu OK and BrCH2C6H40Me/) in DME yields the dendrimer compound 105 (Scheme 22). 

TT-Complexes formed by Seven-Membered and Eight-Membered Carbocyclic Compounds M. A. Bennett, Advances in Organometallic Chemistry 4, 1966, 353. A detailed review. 

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