Buckybowl metal complex

Only very recently some crystal structure determinations of buckybowl metal complexes became available. Petrukhina and Scott reported successful preparation of molecular solids by gas-phase co-deposition of 1 with Rh2(02CCF3)4 which were characterized by X-ray [61]. The resulting solids consisted of ID and 2D networks of Rh2(02CCF3)4 and corannulene units with the [Rh2] fragments // -coordinated... 

Complexation of metals to curved carbon n surfaces has attracted continuous interest since the discovery of fullerenes. So far, fullerenes have been found to act as an -coordination ligand to various transition metals from its eYO- r-surface [1, 2], Other coordination modes in exo complexes were reported in the modified fullerene it systems [3], such as buckyferrocene [4] Fe(CgoMe5)Cp (Cp = cyclopentadienyl). Fullerenes are also known to form the endohedral metal complexes to provide potential materials in carbon chemistry [5, 6], On the other hand, fullerene fragments, termed as n bowls (we use this term in the present chapter, whereas they have been also called open geodesic polyarenes [7] or buckybowls [8]), also possess curved carbon n surfaces, n Bowls have attracted interest in the science of nonplanar -conjugated carbon systems [9-14], From the viewpoint of coordination chemistry, such molecules are quite unique because they can provide not only a convex surface but also an open concave surface for binding (a schematic illustration is shown in Fig. 35.1), which was first addressed by the computational study of hemifullerene (C30H12) in 1993 [15],... 

Buckybowls, in contrast to fullerenes, possess easily accessible convex and concave faces that allow for studies of exo vs. endo preferences of reactivity including metal complex formation. 

The potential formation of transition metal complexes with buckybowls has been of interest since a variety of transition metal complex units were reported to coordinate to buckminsterfullerene C o [54]. Interestingly, in the cases of Ceo complexes the metal is -coordinated to two carbon atoms shared between two 6-membered rings and no -coordinated haptomers were ever reported. 

In contrast, the successful formation of transition metal complexes of buckybowls turned out to be much more challenging. For some time there was only one report of an X-ray characterized buckybowl metal compound (61) the reaction of (Ph3P)2Pt(H2C=CH2) with semibuckminsterfullerene 20 [55]. In this case we... 

A quite different approach to the complexation of corannulene derivatives with transition metals was applied by Chin [65]. His group hydrogenated 1 to its octahy-dro derivative 67 which was subsequently deprotonated by BuLi to the respective fluorene-type anion 68. This species was then used for the formation of two complexes with (CpZrCh) and [Re(CO)3]+. In both cases X-ray structure determination showed // coordination of the metal to the central ring on the exo (convex) side of the very shallow bowl of 68. However, these complexes relate more to the fluorene anion chemistry than to buckybowls. 

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