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Dihapto arene complex

Besides these classical aromatics and polyaromatic hydrocarbons, other very important classes or arene molecules are porphyrins [60, 61], phthalocyanins [61, 62], porphycens [63], calixarenes [64], resorcarenes [64], cydophanes [47], dendrimers [65], elementa-arenes [66], organometallic arene (hexahapto) [67], benzyne (dihapto), and aryl- and benzyl (monohapto) complexes [68], inorganic pyridine and polypyridine complexes [69], fullerenes [70, 71], and... [Pg.10]

Phosphine and phosphite ligands react with arene tricarbonyl complexes of Cr, Mo, and W yielding complexes of the type /ac-(PRg)3M-(CO)3 32, 261, 341-343, 466). Kinetic studies reveal that the reaction proceeds by an 8 2 mechanism 341-343, 466) which is thought to involve the stepwise displacement of the arene via tetrahapto- and dihapto-coordinated arene intermediates 466) ... [Pg.82]

Reduction of /rcMr-RuCl2[Me2PCH2)2]2 by arene radical anions such as sodium naphthalide has been shown to lead to a series of hydridoaryl complexes of the type Ru(H)(aryl)[(Me2PCH2)2]2 63). The hydride structure of the napthalene derivative has been shown in solution (63) and in the solid state 232). However, on the basis of the chemistry of the complexes, the following equilibrium was proposed 63), between a hydride and a small amount of a dihapto-coordinated arene-Ru(O) complex ... [Pg.110]

Little is known about the chemical nature of the recently isolated carbon clusters (C o> C70, Cg4, and so forth). One potential application of these materials is as highly dispersed supports for metal catalysts, and therefore the question of how metal atoms bind to C40 is of interest. Reaction of C o with organometallic ruthenium and platinum re nts has shown that metals can be attached directly to the carbon framework. Ihe native geometry of transition metal, and an x-ray difi action analysis of the platinum complex [(CgHg)3P]2Pt( () -C6o) C4HgO revealed a structure similar to that known for [(C4Hs)3P]2Pt( n -ethylene). The reactivity of C40 is not like that of relatively electron-rich planar aromatic molecules su( as benzene. The carbon-carbon double bonds of C40 react like those of very electron-deficient arenes and alkcnes. [Pg.195]

This chapter will initially cover several aspects of dihapto-coordination of aromatic molecules, including the scope of the dearomatization agent and the aromatic substrate. The primary focus of this work, however, will be the fundamental organic reactions of these complexes with electrophiles and the subsequent reactions of those products. Several applications of this methodology will also be illustrated. Owing largely to its earlier discovery, the majority of the organic transformations reviewed will be with osmium(II), however, recent arene transformations promoted with rhenium(I) and molybdenum(O) will also be discussed, with an emphasis on differences in reactivity compared to those of osmium. [Pg.98]

This precursor is well known to very easily give, with aromatics, complexes of the type [RuCp (r -arene)]+, even when the aromatic bears a double bond in a substituent. Thus, this reaction is a good example of the inability of Ceo to coordinate to the metal in a hexahapto fashion, and on the contrary of its strong tendency to give dihapto complexes. " ... [Pg.227]

Theoretical studies [59] indicate that the lowest unoccupied molecular orbital (LUMO) of such molecules is localized primarily on the acyl carbon atom, similarly to the situation in Fischer complexes. An example of such a compound is shown in Fig. 23.9, where the shortness of the Th-O distance (2.37(2) A) relative to Th-Cg (2.44(2) A) is unprecedented for a dihapto-acyl. A second example of an actinide dihapto-acyl is shown in Fig. 23.10. It should be noted that the orientation of the C-O vector is in the opposite direction from that in Fig. 23.9. The relative magnitudes of the Th-O and Th-C distances appear to reflect both the orientation of the C-O vector and conjugation with the arene n system. The intricate chemistry exhibited by actinide dihapto-acyls is summarized in Fig. 23.11. Important reactions include C-C coupling to form monomeric (10) or dimeric enediolates [57,58,60,61], isomerization to yield enolates (//) [60,62], catalytic hydrogenation to yield alkoxides (/2) [63], CO tetramerization to form dionediolates (13) [62, 64], coupling with ketenes 14), coupling with CO and phosphines 15) [62, 64], and addition to isocyanides to yield ketenimines [62, 64] 16). [Pg.728]


See other pages where Dihapto arene complex is mentioned: [Pg.244]    [Pg.244]    [Pg.174]    [Pg.178]    [Pg.15]    [Pg.298]    [Pg.102]    [Pg.97]    [Pg.252]    [Pg.231]    [Pg.349]    [Pg.175]    [Pg.162]    [Pg.335]    [Pg.336]    [Pg.313]    [Pg.314]    [Pg.95]    [Pg.134]    [Pg.188]   
See also in sourсe #XX -- [ Pg.244 ]




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