Fullerene metal complexes

The heteroatom cy clopentadienyl analog 1,4,2-P2 SbC2 Bu 2 has been coordinated to Tl(l) via equation (2), producing zigzag polymer (2). Thallium coordination has played an important role in crystallographic characterization of metal-fullerene complexes, providing the first structurally characterized pentahapto metal complexes of Ceo (3) and C70 (4). The key to the formation of these monothallium(l) compounds was the arylation of the fullerenes. Methylated Ceo forms a thallium complex as well. ... 

Structural Proposetls for Endohedral Metal-Fullerene Complexes, Chem. Phys. Lett. 187, 1-7 (1991). 

Rubin, Y. Parker, T.C. Kahn S.I. Holliman, C.L. McElvany S.W. Precursors to endohedral metal fullerene complexes synthesis and x-ray structure of a flexible macrocyclic acetylenic cyclophane CgiH h- J. Am. Chem. Soc. 1996, 35(22), 5308-5309. 

Fully Characterized tt-Bonded Metal-Fullerene Complexes"... 

One example of the use of something rather akin to a free-electron model (a model in which the electrons are free to wander over some surface, a surface which is free from nuclei and the complications of their associated point charges), has already been met in Section 10.2, where metal-fullerene complexes were considered. This partial duplication of the discussion makes available to the reader an alternative (and simpler) treatment of much the same material as that which follows. It was felt that this would be helpful since the theory to be developed can pose conceptual difficulties for the student. 

Manolopoulos, D. E., 8c Fowler, P. W. (1991). Structural proposals for endohedral metal-fullerene complexes. Chemical Physics Letters, 187,1-7. 

Except for one early report [17] on the bond dissociation energies for the naked nickel-fullerene eomplex, there is little information available about relative stabilities and dissociation energies of bare metal-fullerene complexes. Why does some metals form strong bonds to fullerenes, while the exohedral metallofiillerene CoCeo has never been observed The aim of our study is to shed light on this and related issues, by exploring which factors play important roles in metal-fullerene interactions and hence determine the bond strengths. To this end we study the interaction between... 

Reaction of 175 with Cgg yields a hydroxy-functionalized fullerene that can be further derivatized. This hydroxy-fullerene was coupled with a porphyrine unit via a polyethyleneglycol-Hnker. This linker can be arranged similarly to a crown-ether to complex metal cations. Complexation is used to tune the distance between the porphyrin imit and the Cgg-moiety and thus tune the donor-acceptor properties of this porphyrin-fuUerene hybrid [177]. 

Reactions of Cjq with metal carbene complexes also yield the [6,6] methano-fullerenes [392]. These adducts are probably not formed via a carbene addition, but via a formal [2-1-2] cycloaddition under formation of a metalla cyclobutane intermediate. The Fischer carbene complex [mefhyl(methoxymethylene)]pentacarbonyl chromium can be utilized to prepare l,2-mefhyl(methoxymethano)-fullerene in 20% yield [392]. A tungsten carbene complex was primarily used to initiate the formation of a polyacetylene polymer, but it was discovered that addition of to the complex-polymer-mixture improves the polymerization and dramatically increases the catalytic activity of the carbene complex [393]. can be integrated into the polymer via carbene addition. 

Unlike zirconium, the group IV metal titanium does not form the hydrometalation product but rather a (r -C5Q)-complex. The first titanium-fullerene complex 1 was prepared by reaction of the bis(trimethylsilyl)-acetylene complex of titanocene with equimolar amounts of Cjq (Scheme 7.1). 

Penta- and hexanuclear clusters of the metals osmium and ruthenium coordinate with the same r ri ri - binding mode as the trinuclear clusters to CgQ. Such complexes are known for the clusters OsjC [75,76], RU5C [77-79], RugC [78], PtRu5C [77] and Rhg [80], In this collection of metal clusters rhenium plays a special role, because it forms a new fullerene-metal sandwich complex, where two C50 are bound to one cluster. 

Occurrence of Fully Characterized Metal-Bound Fullerene Complexes... 

In contrast to the great variety of known organic adducts, there is a relative paucity of metal-containing fullerene complexes. Tables III and IV list (in yearly order of appearance in the literature) all the fully characterized (6, 7) and many of the known [Pg.6]

The optical limiting properties of metal cluster compounds and some fullerene complexes have been studied by RSA, with some of the results... 

Exohedral metal complexes [C6qM]+ are formed by the reaction of Ceo with naked M+ ions (M = Fe, Co, Ni, Cu, Rh, La). ForNi+ the bis-fullerene complex [(C6o)2Ni]+ was also observed. In contrast to the endohedral fullerenes, excitation of these complexes results in facile metal elimination with no associated cage fragmentation. 

The basic themes of metal-metal bonded dimers were established years ago and have remained largely unchanged. However, new aspects of metal-metal bonding have been discovered and in addition, apphcation of metal metal bonded complexes in other areas has grown. Important contributions in emerging fields such as nanomaterials, fuUerene see Carbon Fullerenes) chemistry, combinatorial catalytic research, molecular recognition, and dendrimers have all utihzed metal metal bonded complexes. 

Almost simultaneously, a platinum complex, in which the metal atom is bonded directly to the fullerene cage, was prepared.[Fa91 ] The site of attachment is the 6 6 double bond, as for the osmium derivative. The carbon bond lengths in the fullerene complexed with Pt are also similar to neat Ceo and to the Os derivative described above. Further details and other metal attachments are described in a review paper.[Fa92]... 

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