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This study examines the intrinsic structural and optoelectronic properties of the neutral indeno[1,2-b]fluorene skeleton as well as those of the corresponding anion radical and dianion. We report their characterization by analysis of solid-state structures and EPR, NMR, and absorbance spectra. Additionally, 20 popular density functional theory methods are used to evaluate their performance for predicting NMR chemical shifts, EPR hyperfine coupling constants, and low-energy transitions of the absorbance spectrum to act as a guide for future studies. This information can be used for a better understanding and tuning of the electron-transporting/accepting ability of the indenofluorene core for use in organic photovoltaics and organic field effect transistors.

The first X-ray structural characterization of bicorannulenyl dianion has been accomplished for two alkali metal salts, [Li+(THF)4]2[C40H182–] (1) and [Cs+(18-crown-6)]2[C40H182–] (2). This crystallographic study revealed the biaryl stereochemistry, geometry transformation upon acquiring two electrons, and different binding preferences of Li+ vs Cs+ ions in the solid-state products.

Two new rubidium salts of the bowl-shaped corannulene monoanion radical C20H10•– (1•–), [Rb(15-crown-5)2+][C20H10–] (2) and [Rb(dicyclohexano-18-crown-6)+][C20H10–] (3), have been synthesized and structurally characterized in this work. An excess of 15-crown-5 ether provided full encapsulation of the rubidium ion in [Rb(15-crown-5)2]+, which precluded metal-directed π interactions with the anionic surface of C20H10•– in the solid-state structure of 2. The use of more sterically demanding dicyclohexano-18-crown-6 ether prevented the formation of polymeric chains previously seen with 18-crown-6 ether and favored the isolation of the discrete contact ion pair 3. Complex 3 is built on a convex η6 coordination of Rb+ to C20H10•–, reaffirming the exo-binding preference of rubidium ions toward the singly charged corannulene bowl. A rubidium salt of the planar coronene monoanion radical C24H12•– (4•–), [Rb(18-crown-6)+][C24H12–] (5), has also been prepared and structurally characterized to reveal a new binding mo...

Mono-, di- and tetraanions of rubrene, (C42H28, Rub0), were generated by the controlled reduction of neutral polyarene with various alkali metals in the appropriate solvent. The X-ray diffraction studies of the resulting adducts of Rub1–, Rub2– and Rub4– with alkali-metal ions revealed the distortion of the rubrene core upon the stepwise acquisition of electrons. Coordination of the Cs+ ion and a noticeable deformation of Rub1– are observed at the first reduction step. Two types of rubrene dianions showing an essentially different conformation and coordination environment for the central tetracene core have been seen in the cesium adduct of Rub2–. Various types of supramolecular assembly between the tetrareduced rubrene anion, Rub4–, and lithium or rubidium cations have been found in the corresponding products in the solid state. The structures of rubrene anions and their aggregation with alkali-metal ions in solution have been studied by ESR and multinuclear NMR (1H, 13C, 7Li and 133Cs) spectroscopy.

Single-crystal X-ray diffraction studies of two polyaromatic radical anions crystallized as sodium salts, namely [Na(DME)(3) ](+)[C(20) H(10)(-)] (1) and [Na(DME)(3)](+)[C(24)H(12)(-)] (2) are reported. This allowed the first structural evaluation of Jahn-Teller (JT) effects for monoreduced circulenes and a comparison between bowl-shaped corannulene and planar coronene. The C(s) and D(2h) symmetrical distortions are found to fit the experimental data for C(20)H(10)(·-) and C(24)H(12)(·-), respectively. The continuous symmetry measure (CSM) analysis was carried out to provide a quantitative measure of the JT distortions in 1 and 2. In addition, the X-ray crystallographic results were fully supported by DFT calculations.

The first successful high-yield solution synthesis of homobimetallic Bi(2)(O(2)CCF(3))(4) (1), as well as heterobimetallic BiRh(O(2)CCF(3))(4) (2) and BiRh(O(2)CCF(2)CF(3))(4) (3), complexes is reported. It is based on one-pot reduction reactions starting from Bi(III) and Rh(II) carboxylates and using Bi metal as a reducing agent. The presence of small amounts of diphenyl ether was found to facilitate this reaction, most probably because of its good solubilizing and π-stabilizing abilities. The latter is illustrated by the isolation and structural characterization of a π-adduct of 1 with diphenyl ether, [Bi(2)(O(2)CCF(3))(4)·1/2Ph(2)O]. Importantly, the new approach expands to solution the chemistry of Bi(II) that was previously limited to the solid state only. The solution procedure developed for the preparation of heterometallic BiRh(O(2)CCF(3))(4) is now one step shorter and gives the product in excellent yield compared with the previously reported method based on sublimation-deposition technique. It is also performed on a greater scale (~10-20 times) and makes further scale-up feasible, if needed. Moreover, it eliminates the isolation of the hard-to-handle unsolvated Bi(II) trifluoroacetate used earlier as a starting material. A new polymorph of BiRh(O(2)CCF(3))(4) (2) was crystallized from solution in this work. The solution approach was also applied to the synthesis of a new heterobimetallic carboxylate with perfluorinated propionate ligands, BiRh(O(2)CCF(2)CF(3))(4) (3). All products are fully characterized by spectroscopic and single crystal X-ray diffraction methods. Complexes 2 and 3 exhibit similar solid state structures based on heterobimetallic paddlewheel units forming infinite 1D chains through intermolecular Rh···O interactions.

The intercalation of alkali metal ions into carbon-based aromatic systems is of great interest in materials science due to the increased need for stable anode materials with high capacity of energy storage. Currently, graphite, a sp2-hybirdized carbon network, is the key anode component in rechargeable Li-ion batteries. Carbon allotropes with nonplanar π-surfaces, ranging from fullerenes to nanotubes, are now under investigation as prospective anode materials. The curved carbon networks of fullerenes and nanotubes are often modeled by open bowl-shaped polyaromatic hydrocarbons, such as the smallest curved fullerene fragment, corannulene (C20H10). One of the most fascinating properties of such bowl-shaped polyarenes and fullerenes is their ability to reversibly uptake and delocalize extra electrons upon multi-electron reduction without significant rearrangement and deformation of their carbon framework [1,2]. Notably, the anode material fabricated from corannulene shows a high reversible lithium capacity (602 mAh/g). This is almost twice as high as the theoretical capacity of the commonly used fully lithiated planar graphite material (LiC6, 372 mAh/g). In our work, we target the X-ray structural elucidation of metal intercalation patterns of carbon-rich curved polyarenes with light alkali metal ions, such as Li and Na, and compare those with extended planar polyaromatic systems. Recently, we expanded this study to the light alkaline earth metal, Mg, as its atomic radius is very close to that of Li. In addition, magnesium is cost effective and abundant, and thus presents great interest in the emerging energy storage technologies.