Marina A. Petrukhina

A Main Group Metal Sandwich: Five Lithium Cations Jammed Between Two Corannulene Tetraanion Decks

Characterization of the lithium-ion arrangement between two carbon sheets may ultimately aid in the design of battery electrodes. Lithium-coordinated polyaromatic anions such as tetrareduced corannulene, C20H104− (14−), are useful substrates to model and ultimately improve the graphitic electrodes in lithium-ion (Li+) batteries. Previous studies suggested that 14− forms dimers encasing four Li+ ions in solution. Here, we report a single-crystal x-ray diffraction analysis confirming the formation of a sandwich-type supramolecular aggregate with a high degree of alkali metal intercalation. In contrast to the prior model, our data reveal that five Li+ ions are sandwiched between the two tetrareduced corannulene decks, and 7Li nuclear magnetic resonance spectroscopy delineates a conserved structure in tetrahydrofuran solution. Remarkably, the sandwich is robust in both solution and solid states even in the presence of crown ethers that compete for Li+ coordination. These results should help elucidate Li+ intercalation motifs between curved carbon surfaces more broadly.

Selective endo and exo binding of alkali metals to corannulene.

The ion size matters: the structures of corannulene monoanions crystallized with Cs(+) and Rb(+) ions in the presence of [18]crown-6 reveal the intrinsic binding preferences of alkali metals and allow evaluation of the bowl deformation caused by negative charge distribution and metal binding. The large cesium cation coordinates exclusively to the concave face of C(20) H(10)(-), whereas the smaller rubidium cation exhibits convex binding.

A Buckybowl with a Lot of Potential: C5-C20H5(CF3)5†

Lots of potential: a trifluoromethylated corannulene, C(5)-C(20)H(5)(CF(3))(5), has been prepared and characterized spectroscopically and by X-ray crystallography. The structure exhibits a highly ordered bowl stacking that is unusual for corannulenes with acyclic substituents. The first reduction of C(5)-C(20)H(5)(CF(3))(5) is anodically shifted by 0.95 V, making it the strongest corannulene-based electron acceptor to date.

How Charging Corannulene with One and Two Electrons Affects Its Geometry and Aggregation with Sodium and Potassium Cations

Bowl-shaped mono- and dianions are prepared by reduction of corannulene (C(20)H(10), 1) with sodium and potassium metals in the presence of [18]crown-6 ether. Single-crystal X-ray diffraction studies of two sodium salts, [Na(THF)(2)([18]crown-6)](+)[1(-)] (2a) and [Na([18]crown-6)](+)[1(-)] (2b), reveal the presence of naked corannulene monoanions 1(-) in both cases. In contrast, the potassium adduct, [K([18]crown-6)](+)[1(-)] (3), shows an η(2)-binding of the K(+) ion to the convex face of 1(-). For the first time, corannulene dianions have been isolated as salts with sodium, [Na(2)([18]crown-6)](2+)[1(2-)] (4a) and [Na(THF)(2)([18]crown-6)](+)[Na([18]crown-6)](+)[1(2-)] (4b), and potassium counterions, [K([18]crown-6)](2)(+)[1(2-)] (5). Their structural characterization reveals geometry perturbations upon addition of two electrons to a bowl-shaped polyarene. It also demonstrates η(5)- or η(6)-binding of metals to the curved carbon surface of 1(2-), depending on the crystallization conditions. Both mono- and doubly-charged corannulene bowls show the preferential exo binding of Na(+) and K(+) ions in all investigated compounds. Various types of C-H···π interactions are found in the crystals of 2-5. The UV/Vis, ESR, and (1)H NMR spectroscopic studies of 2-5 indicate different coordination environment of corannulene anions in solution, depending on the metal ion.

Fragments of fullerenes and carbon nanotubes : designed synthesis, unusual reactions, and coordination chemistry

PREFACE vii FOREWORD xi CONTRIBUTORS xiii ACRONYMS xvii 1 MOLECULAR CLIPS AND TWEEZERS WITH CORANNULENE PINCERS 1 Andrzej Sygula and Willard E. Collier 2 SYNTHESIS OF BOWL-SHAPED AND BASKET-SHAPED FULLERENE FRAGMENTS VIA BENZANNULATED ENYNE---ALLENES 41 Kung K. Wang, Hu Cui, and Bo Wen 3 ANIONS OF BUCKYBOWLS 63 David Eisenberg, Roy Shenhar, and Mordecai Rabinovitz 4 CURVED p-CONJUGATED STABLE OPEN-SHELL SYSTEMS POSSESSING THREE-DIMENSIONAL MOLECULAR/ELECTRONIC SPIN STRUCTURES 95 Yasushi Morita and Akira Ueda 5 EXPERIMENTAL AND CALCULATED PROPERTIES OF FULLERENE AND NANOTUBE FRAGMENTS 135 Derek R. Jones, Praveen Bachawala, and James Mack 6 COORDINATION PREFERENCES OF BOWL-SHAPED POLYAROMATIC HYDROCARBONS 157 Alexander S. Filatov and Marina A. Petrukhina 7 SUMANENES: SYNTHESIS AND COMPLEXATION 187 Toshikazu Hirao and Toru Amaya 8 r-BONDED TRANSITION METAL COMPLEXES OF POLYCYCLIC AROMATIC CARBON COMPOUNDS 205 Paul R. Sharp 9 HEMISPHERICAL GEODESIC POLYARENES: ATTRACTIVE TEMPLATES FOR THE CHEMICAL SYNTHESIS OF UNIFORM-DIAMETER ARMCHAIR NANOTUBES 235 Anthony P. Belanger, Katharine A. Mirica, James Mack, and Lawrence T. Scott 10 AROMATIC BELTS AS SECTIONS OF NANOTUBES 259 Gaston R. Schaller and Rainer Herges 11 CYCLOPARAPHENYLENES: THE SHORTEST POSSIBLE SEGMENTS OF ARMCHAIR CARBON NANOTUBES 291 Xia Tian and Ramesh Jasti 12 CONJUGATED MOLECULAR BELTS BASED ON 3D BENZANNULENE SYSTEMS 311 Masahiko Iyoda, Yoshiyuki Kuwatani, Tohru Nishinaga, Masayoshi Takase, and Tomohiko Nishiuchi 13 TOWARD FULLY UNSATURATED DOUBLE-STRANDED CYCLES 343 Malte Standera and A. Dieter Schl uter 14 BENT PYRENES: SPRINGBOARDS TO AROMATIC BELTS? 367 Graham J. Bodwell, Gandikota Venkataramana, and Unikela Kiran Sagar INDEX 401

Foregoing rigidity to achieve greater intimacy.

Interactions between the surfaces of planar and nonplanar molecules have generated considerable interest in materials chemistry as critical elements for understanding twodimensional supramolecular assembly, molecular and chiral recognition, and heterogeneous catalysis. Carbon-rich balland bowl-shaped polyaromatic molecules, such as fullerenes and fullerene fragments or buckybowls, figure prominently in these studies. Fullerenes have been found to form solid constructs with planar metalloporphyrins with remarkably close contacts but without the need for matching their convex and concave faces. Molecular self-organization of nonplanar polyaromatic bowls on a planar metal surface introduces the interesting additional factor of symmetry mismatch. Studies of ordered structures formed by weakly bound corannulene, C20H10, on the Cu(110) surface examined by scanning tunneling microscopy (STM) have revealed interesting insights into their molecular interactions. However, the overall effect of these interactions on the geometry of the corannulene bowl could not be evaluated by the STM method. In this work, we selected a system that allowed us to investigate the mutual structural influences of bowl-shaped polyarenes and a planar polynuclear metal unit upon their attractive interaction (Figure 1). Curving of the planar

C20H4(C4F8)3: A Fluorine-Containing Annulated Corannulene that Is a Better Electron Acceptor Than C60†

At sixes and sevens: The reaction of corannulene with 35 equivalents of 1,4-C4F8I2 is an efficient and a relatively selective process that yields two main products in which six H atoms are substituted with three C4F8 moieties that form six- and seven-membered rings. Low-temperature photoelectron spectroscopy showed the electron affinity of the major isomer (shown) exceeds that of C60 (2.74±0.02 and 2.689±0.008 eV, respectively).

A Strain‐Releasing Trap for Highly Reactive Electrophiles: Structural Characterization of Bowl‐Shaped Arenium Carbocations

In addition toits own unique properties, corannulene serves as a primarymodel for both theoretical and experimental studies for avariety of curved carbon networks ranging from fullerenes tonanotubes.Todate,theorganicreactionsofcorannulenehavebeen mainly limited tothe derivatization of its exteriorand tosynthetic transformations of rim-bound functional groups.

Studies of tetrakis(trifluoroacetate) dirhodium: Part 4. Solventless synthesis of Rh2(O2CCF3)2(CO)4 combined with Rh2(O2CCF3)4, a compound with infinite chains of rhodium atoms

Abstract By reaction of Rh2(O2CCF3)4 and Mo(CO)6 in an evacuated sealed tube placed in a thermal environment where there is a thermal gradient (125–120°C), we have obtained a compound in which one Rh2(O2CCF3)4 unit is sandwiched between two Rh2(O2CCF3)2(CO)4 units, to give an essentially linear array of six rhodium atoms, with Rh–Rh distances of 2.960(1), 2.790(1) and 2.412(1) A. These arrays of six rhodium atoms are then linked into infinite chains which lie parallel in the crystal, with Rh to Rh contacts of 3.062(1) A. The crystals are markedly dichroic and relatively air stable.

Clamshell Opening in the Mixed‐Metal Supramolecular Aggregates Formed by Fourfold Reduced Corannulene for Maximizing Intercalated Metal Content

The first members of a new class of supramolecular organometallic compounds with mixed-alkali-metal cluster cores, LiK5 and Li3 K3 , sandwiched between two four-fold reduced corannulene decks are prepared and fully characterized. The triple-decker supramolecular anions, [(C20 H10 (4-) )(LiK5 )(6+) (C20 H10 (4-) )](2-) and [(C20 H10 (4-) )(Li3 K3 )(6+) (C20 H10 (4-) )](2-) , illustrate a record ability of bowl-shaped and highly charged corannulene to provide all its sites, five benzene rings fused to a central five-membered ring, for binding of six alkali-metal ions. The previously unseen engagement of the hub-site of C20 H10 (4-) in lithium binding is accompanied by unprecedented shifts up to -24 ppm in (7) Li NMR spectra. The discussion of product formation mechanism, augmented by calculations, is provided.