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Unusual intermolecular π-stacking in a new charge transfer salt of pyrene (Py), (Py)2+(Ga2Cl7)−, has been observed.

The chemical reduction of a π-expanded COT derivative, octaphenyltetrabenzocyclooctatetraene (1), with lithium or sodium metals in the presence of secondary ligands affords a new doubly-reduced product (1

Aromaticity is one of the most deeply rooted concepts in chemistry. But why, if two-thirds of existing compounds can be classified as aromatic, is there no consensus on what aromaticity is? σ−, π−, δ−, spherical, Möbius, or all-metal aromaticity… why are so many attributes needed to specify a property? Is aromaticity a dubious concept? This perspective aims to reflect where the aromaticity community is and where it is going.

The stepwise chemical reduction of a molecular warped nanographene (WNG) having a negatively curved π-surface and defined C80 H30 composition with Cs metal used as the reducing and complexing agent allowed the isolation of three different reduced states with one, two, and three electrons added to its π-conjugated system. This provided a unique series of nanosized carbanions with increasing negative charge for in-depth structural analysis of consequences of controlled electron charging of non-planar nanographenes, using X-ray crystallographic and computational tools. The 3D molecular electrostatic potential (MEP) maps identified the negative charge localization at the central part of the WNG surface where selective coordination of Cs+ ions is confirmed crystallographically. In-depth theoretical investigation revealed a complex response of the WNG to the stepwise electron acquisition. The extended and contorted π-surface of the WNG undergoes subtle swinging distortions that are accompanied by notable changes in the electronic structure and site-dependent aromaticity of the resulting carbanions.

This study explores a bottom-up approach toward negatively curved carbon allotropes from octabenzo[8]circulene, a negatively curved nanographene. Stepwise chemical reduction reactions of octabenzo[8]circulene with alkali metals lead to a unique highly reduced hydrocarbon pentaanion, which is revealed by X-ray crystallography suggesting a local view for the reduction and alkali metal intercalation processes of negatively curved carbon allotropes. Polymerization of the tetrabromo derivative of octabenzo[8]circulene by the nickel-mediated Yamamoto coupling reaction results in a new type of porous carbon-rich material, which consists of a covalent network of negatively curved nanographenes. It has a specific surface area of 732 m2 g-1 and functions as anode material for lithium ion batteries exhibiting a maximum capacity of 830 mAh·g-1 at a current density of 100 mA·g-1. These results indicate that this covalent network presents the key structural and functional features of negatively curved carbon allotropes.

The consequences of four-electron addition to [8]cycloparaphenylene ([8]CPP, 1) have been evaluated crystallographically, revealing a significant core deformation. The structural analysis exposes an elliptical distortion observed upon electron transfer, with the deformation parameter (D.P.) increased by 28% in comparison with neutral [8]CPP. The C–C bond length alteration pattern also indicates a quinoidal structural rearrangement upon four-fold reduction. The large internal cavity of [8]CPP4− allows the encapsulation of two {K+(THF)2} cationic moieties with two additional cations bound externally in the solid-state structure of [{K+(THF)2}4([8]CPP4−)]. The experimental structural data have been used as a benchmark for the comprehensive theoretical description of the geometric changes and electronic properties of the highly-charged [8]CPP4− nanohoop in comparison with its neutral parent. While neutral [8]CPP and the [8]CPP2− anion clearly show aromatic behavior of all six-membered rings, subsequent addition of two more electrons completely reverses their aromatic character to afford the highly-antiaromatic [8]CPP4− anion, as evidenced by structural, topological, and magnetic descriptors. The disentanglement of electron transfer from metal binding effects allowed their contributions to the overall core perturbation of the negatively-charged [8]CPP to be revealed. Consequently, the internal coordination of potassium cations is identified as the main driving force for drastic elliptic distortion of the macrocyclic framework upon reduction., Structural and theoretical analysis of a highly-charged [8]cycloparaphenylene reveals drastic elliptic distortion and unique metal encapsulation of the macrocyclic host upon reduction.

Chemical reduction of sym-dibenzo[a,e]cyclooctatetraene (DBCOT, 1) has been investigated using group 1 metals ranging from Li to Cs as the reducing agents. With all alkali metals, DBCOT readily und...

The chemical reduction of a π‐expanded polycyclic framework comprising a cyclooctatetraene moiety, octaphenyltetrabenzocyclooctatetraene, with lithium metal readily affords the corresponding tetra‐anion instead of the expected aromatic dianion. As revealed by X‐ray crystallography, the highly contorted tetra‐anion is stabilized by coordination of two internally bound Li+, while two external cations remain solvent separated. The variable‐temperature 7Li NMR spectra in THF confirm the presence of three types of Li+ ions and clearly differentiate internal binding, consistent with the crystal structure. Density‐functional theory calculations suggest that the formation of the highly charged tetra‐reduced carbanion is stabilized through Li+ coordination under the applied experimental conditions., A highly contorted π‐expanded polycyclic tetra‐anion comprising a cyclooctatetraene moiety is readily formed upon reduction of the neutral precursor with lithium metal. The highly charged carbanion crystallizes with four lithium counterions, two of which stabilize the contorted structure through internal coordination. Density‐functional theory calculations rationalize the unexpected formation of the tetra‐anion and provide insights into its electronic properties.

We describe reductive dehydrogenative cyclizations that form hepta-, nona- and decacyclic anionic graphene subunits from mono- and bis-helicenes with an embedded five-membered ring. The reaction of bis-helicenes can either proceed to the full double annulation or be interrupted by addition of molecular oxygen at an intermediate stage. The regioselectivity of the interrupted cyclization cascade for bis-helicenes confirms that relief of antiaromaticity is a dominant force for these facile ring closures. Computational analysis reveals the unique role of the preexisting negatively charged cyclopentadienyl moiety in directing the 2nd negative charge at a specific remote location and, thus, creating a localized antiaromatic region. This region is the hot-spot that promotes the initial cyclization. Computational studies, including MO analysis, molecular electrostatic potential maps, and NICS(1.7)ZZ calculations evaluate the interplay of the various effects including charge delocalization, helicene strain release, and antiaromaticity. The role of antiaromaticity relief is further supported by efficient reductive closure of the less strained mono-helicenes where the relief of antiaromaticity promotes the cyclization even when the strain is substantially reduced. The latter finding significantly expands the scope of this reductive alternative to the Scholl ring closure.

Chemical reduction of several cycloparaphenylenes (CPPs) ranging in size from [8]CPP to [12]CPP has been investigated with potassium metal in THF. The X-ray diffraction characterization of the resulting doubly-reduced [n]CPPs provided a unique series of carbon nanohoops with increasing dimensions and core flexibility for the first comprehensive structural analysis. The consequences of electron acquisition by a [n]CPP core have been analyzed in comparison with the neutral parents. The addition of two electrons to the cyclic carbon framework of [n]CPPs leads to the characteristic elliptic core distortion and facilitates the internal encapsulation of sizable cationic guests. Molecular and solid-state structure changes, alkali metal binding and unique size-dependent host abilities of the [n]CPP2− series with n = 6–12 are discussed. This in-depth analysis opens new perspectives in supramolecular chemistry of [n]CPPs and promotes their applications in size-selective guest encapsulation and chemical separation., The series of doubly-reduced cycloparaphenylenes (CPPs) with increasing dimensions and flexibility shows the size-dependent structural changes and enhanced host abilities.

Chemical reduction of a benzo-fused double [7]helicene (1) with two alkali metals, K and Rb, provided access to three different reduced states of 1. The doubly-reduced helicene 12- has been characterized by single-crystal X-ray diffraction as a solvent-separated ion triplet with two potassium counterions. The triply- and tetra-reduced helicenes, 13- and 14- , have been crystallized together in an equimolar ratio and both form the contact-ion complexes with two Rb+ ions each, leaving three remaining Rb+ ions wrapped by crown ether and THF molecules. As structural consequence of the stepwise reduction of 1, the central axis of helicene becomes more compressed upon electron addition (1.42 A in 14- vs. 2.09 A in 1). This is accompanied by an extra core twist, as the peripheral dihedral angle increases from 16.5° in 1 to 20.7° in 14- . Theoretical calculations provided the pattern of negative charge build-up and distribution over the contorted helicene framework upon each electron addition, and the results are consistent with the X-ray crystallographic and NMR spectroscopic data.

One-electron reduction of bowl-shaped indenocorannulene, C26H12, with Rb metal in THF affords [{Rb+(18-crown-6)}2(C26H12–C26H12)2−]·4THF, as confirmed by single-crystal X-ray diffraction. The product consists of a dimeric σ-bonded dianion (C–C, 1.568(7) A) having two endo-η6 coordinated {Rb+(18-crown-6)} moieties (Rb–C, 3.272(4)–3.561(4) A). The (C26H12–C26H12)2− dimer represents the first crystallographically confirmed example of spontaneous coupling for indenocorannulene monoanion radicals, C26H12˙−. Comprehensive theoretical investigation of the new dimer confirms the single σ-bond character of the linker and reveals a significant increase of both thermodynamic and kinetic stability of [σ-(C26H12)2]2− in comparison with analogues formed by such π-bowls as corannulene and its dibenzo-derivative. The in-depth computational analysis and direct comparison of the series demonstrates the effect of curvature on radical coupling processes, allowing control over stability and reactivity of bowl-shaped π-radicals.

A new class of heterotrimetallic COT-based self-assemblies accommodates metals from groups I–III in three different oxidation states and enables tuning of electronic and magnetic properties.

Incorporation of a five-membered ring into a helicene framework disrupts aromatic conjugation and provides a site for selective deprotonation. The deprotonation creates an anionic cyclopentadienyl unit, switches on conjugation, leads to a >200 nm red-shift in the absorbance spectrum and injects a charge into a helical conjugated π-system without injecting a spin. Structural consequences of deprotonation were revealed via analysis of a monoanionic helicene co-crystallized with {K+ (18-crown-6)(THF)} and {Cs+2 (18-crown-6)3 }. UV/Vis-monitoring of these systems shows a time-dependent formation of mono- and dianionic species, and the latter was isolated and crystallographically characterized. The ability of the twisted helicene frame to delocalize the negative charge was probed as a perturbation of aromaticity using NICS scans. Relief of strain, avoidance of antiaromaticity, and increase in charge delocalization assist in the additional dehydrogenative ring closures that yield a new planarized decacyclic dianion.

The dianion and dication of tetramesityl-substituted tetracyclopentatetraphenylene, a circulene consisting of alternating five- and six-membered rings, have been generated by reduction with alkali metals and oxidation with antimony(V) halides, respectively. They are theoretically predicted to adopt double annulenoid structures called annulene-within-an-annulene models in which the outer and inner conjugation circuits are significantly decoupled. The theoretical structures were experimentally proven by X-ray crystallographic analyses and the electronic configurations were supported by MCD spectra. Based on the

Chemical reduction of pentacene (C

The monoanion of triphenylene (C18H12, 1) was generated in THF using several alkali metals (Na, K, Rb, and Cs) as reducing agents and crystallized with the corresponding cations in the presence of 18-crown-6 ether. The UV-vis spectroscopy points to the metal-dependent coordination environment of the triphenylene monoanion-radicals, 1·-, in solution. The X-ray diffraction characterization confirmed the formation of a solvent-separated ion pair (SSIP) with sodium ions, [{Na+(18-crown-6)(THF)2}(1·-)] (2), and three contact-ion pair (CIP) complexes formed by larger alkali metal ions, [{K+(18-crown-6)}(1·-)] (3), [{Rb+(18-crown-6)}(1·-)] (4), and [{Cs+(18-crown-6)}(1·-)] (5). Structural analysis of the series reveals a notable geometry perturbation of the triphenylene framework in 2 caused by one-electron acquisition, which is further enhanced by direct metal binding in 3-5. This has been correlated with the aromaticity changes and charge redistribution upon one-electron reduction of 1, as revealed by the computational studies. The EPR spectroscopy and magnetic susceptibility measurements confirm antiferromagnetic interactions corresponding to an S = 1/2 system in the solid state. The magnetic behavior of 3-5 correlates with the arrangement of triphenylene radicals in the crystal structures. All three compounds exhibit antiferromagnetic (AFM) interactions between S = 1/2 radicals in the solid state, but the exchange coupling in 4 and 5 is notably stronger than that in 3, which leads to AFM ordering at 3.8 K in 4 and at 2.0 K in 5. The magnetic phase transitions in 4 and 5 can be interpreted as originating from interactions between the chains of the AFM-coupled S = 1/2 radicals.

One-electron reduction of corannulene, C20 H10 , with Li metal in diglyme resulted in crystallization of [{Li+ (diglyme)2 }4 (C20 H10.- )2 (C20 H10 -C20 H10 )2- ] (1), as revealed by single-crystal X-ray diffraction. This hybrid product contains two corannulene monoanion-radicals along with a dianionic dimer, crystallized with four Li+ ions wrapped by diglyme molecules. The dimeric (C20 H10 -C20 H10 )2- anion provides the first crystallographically confirmed example of spontaneous radical dimerization for C20 H10.- . The C-C bond length between the two C20 H10.- bowls of 1.588(5) A is consistent with the single σ-bond character of the linker. The trans-disposition of two bowls in the centrosymmetric (C20 H10 -C20 H10 )2- dimer is observed with the torsion angle around the central C-C bond of 180°. Comprehensive theoretical analysis of formation/decomposition processes of the dimeric dianion has been carried out in order to evaluate the nature of bonding and energetics of the C20 H10.- coupling. It is found that such σ-bonded dimers are thermodynamically unstable due to large preparation energy and repulsive Pauli component of the bonding, but kinetically persistent due to a high energy barrier provided by the existing spin-crossing point.

Barium (II) π-complexes with two planar polycyclic aromatic hydrocarbons (PAHs), anthracene and fluoranthene, have been prepared by direct alkaline earth metal reduction reactions in THF in the presence of 1,2-diiodoethane (DIE), used as an activator. The products have been crystallographically characterized to reveal their mixed-ligand composition, {[Ba(I)(THF)3]22+[C14H10]2–} (1) and {[Ba(I)(THF)3]22+[C16H10]2–} (2). A similar strontium (II) product, {[Sr(I)(THF)4]22+[C10H8]2-} (3), has been synthesized using potassium-naphthalenide ligand-exchange reaction starting with SrI2. In 1 and 2, Ba(II) ions are π-complexed by doubly-reduced PAHs with the planarity of the dianions being preserved upon reduction and metal binding. In contrast, the naphthalene dianion in 3 adopts a non-planar geometry with a dihedral angle of 15.2°. The M–Ccentroid distances of 2.754 (6) A and 2.755 (14) A in 1 and 2, respectively, are longer than that in 3 (2.600 (2) A). The coordination environment of alkaline earth metal ions is completed by iodide ligands and coordinated THF molecules. The X-ray structural investigation confirmed the formation of the iodide-bridged 1D polymers in barium products, {[Ba (μ-I) (THF)3]22+[C14H10]2–}∞ (1) and {[Ba (μ-I) (THF)3]22+[C16H10]2–}∞ (2) vs. a discrete strontium complex with terminal iodide ligands in 3.

Mono- and dianions of 2-tert-butyl-3a2 -azapentabenzo[bc,ef,hi,kl,no]corannulene (1 a) were synthesized by chemical reduction with sodium and cesium metals, and crystallized as the corresponding salts in the presence of 18-crown-6 ether. X-ray diffraction analysis of the sodium salt, [{Na+ (18-crown-6)(THF)2 }3 {Na+ (18-crown-6)(THF)}(1 a2- )2 ], revealed the presence of a naked dianion. In contrast, controlled reaction of 1 a with Cs allowed the isolation of singly and doubly reduced forms of 1 a, both forming π-complexes with cesium ions in the solid state. In [{Cs+ (18-crown-6)}(1 a- )]⋅THF, asymmetric binding of the Cs+ ion to the concave surface of 1 a- is observed, whereas in [{Cs+ (18-crown-6)}2 (1 a2- )], two Cs+ ions bind to both the concave and convex surfaces of the dianion. The present study provides the first successful isolation and characterization of the reduced products of heteroatom-containing buckybowl molecules.

The reaction of Re2 (CO)8 (μ-C6 H5 )(μ-H), 1 with corannulene (C20 H10 ) yielded the product Re2 (CO)8 (μ-H)(μ-η2 -1,2-C20 H9 ), 2 (65 % yield) containing a Re2 metalated corannulene ligand formed by loss of benzene from 1 and the activation of one of the CH bonds of the nonplanar corannulene molecule by an oxidative-addition to 1. The corannulenyl ligand has adopted a bridging η2 -σ+π coordination to the Re2 (CO)8 grouping. Compound 2 reacts with a second equivalent of 1 to yield three isomeric doubly metalated corannulene products: Re2 (CO)8 (μ-H)(μ-η2 -1,2-μ-η2 -10,11-C20 H8 )Re2 (CO)8 (μ-H), 3 (35 % yield), Re2 (CO)8 (μ-H)(μ-η2 -2,1-μ-η2 -10,11-C20 H8 )Re2 (CO)8 (μ-H), 4 (12 % yield), and Re2 (CO)8 (μ-H)(μ-η2 -1,2-μ-η2 -11,10-C20 H8 )Re2 (CO)8 (μ-H), 5 (12 % yield), by a second CH activation on a second rim double bond on the corannulene molecule. The isomers differ by the relative orientations of the coordinated Re2 (CO)8 (μ-H) groupings. All new products were characterized structurally by single crystal X-ray diffraction analysis.

In-depth theoretical analysis of the consequences of methylation of the rim sites of corannulene is completed. The full set of derivatives ranging from parent C20H10 to fully substituted C20(CH3)10 has been evaluated, revealing consistent trends along the series. The controlled one-electron chemical reduction of selected methylated corannulenes, such as monomethyl- (C20H9(CH3)), sym-pentamethyl- (1,3,5,7,9-C20H5(CH3)5), and decamethylcorannulene (C20(CH3)10) has also been investigated. Cesium metal was used as a reducing agent to access endo complexes having cesium ion placed inside the concave cavity of the monoreduced bowls. Two products, [{Cs+(18-crown-6)}{C20H9(CH3)−}] (1) and [{Cs+(18-crown-6)}{C20H5(CH3)5–}] (2), have been crystallized in the presence of 18-crown-6 ether and crystallographically characterized to confirm the concave cesium ion coordination. The direct structural comparison of 1 and 2 with the complex of unsubstituted corannulene, [{Cs+(18-crown-6)}{C20H10–}] (3), has been conducted. ...

Two new organometallic cyclooctatetraenyl complexes of the type [M2(COT)3(THF)2] (M = Y and La) have been prepared, using optimized synthetic procedures, and fully characterized by X-ray diffraction analysis, IR and 1H NMR spectroscopies. The structures can be represented as formed by the double-decker [M(COT)2]- anion with an asymmetrically bound cationic [M(COT)(THF)2]+ unit. The COT rings in the anionic sandwich are not equidistant from the metal with the M-COTcentroid distances measuring at 1.991(5) A and 2.074(5) A for [Y(COT)2]-vs. 2.045(4) A and 2.154(5) A for [La(COT)2]-. The sandwich fragments are η2-coordinated to the second metal center with the average M-C distances of 2.837(4) A and 2.879(5) A for yttrium and lanthanum complexes, respectively. The M-COTcentroid distances in the cationic unit are 1.962(4) A for the former and 2.009(2) A for the latter.

The unsolvated Cu(II) complex with bis(pentafluorobenzoyl)methanide ligand (L, C6F5COCHCOC6F5−) is prepared and crystallized as [CuL2] (1) using gas phase sublimation-deposition at 150 °C. The X-ray crystallographic characterization confirmed the centrosymmetric mononuclear structure of 1 with a square planar geometry around Cu(II) (Cu–Oav 1.9149(8) A). The reaction of 1 with sodium hexafluoroacetylacetonate [Na(hfac)] in a solvent-free environment afforded [Na2Cu2L4(hfac)2] (2), the first heterometallic Na–Cu β-diketonate characterized by single-crystal X-ray diffraction. In the centrosymmetric tetranuclear structure of 2, a dimeric [Na(hfac)]2 unit is sandwiched between two CuL2 units. The L-ligands function as chelating-bridging between Cu and Na through one of their O-atoms. The hfac ligands are chelating-bridging between Cu and Na and between Na(1) and Na(1A) through both O-atoms. In addition to the five primary Na–O interactions (av. 2.4109(17) A), three secondary Na–F contacts (av. 2.6006(15) A) contribute to the overall distorted square antiprismatic coordination environment for Na. The geometry of Cu is square pyramidal with Cu–O(L) distances averaging at 1.922(14) A and Cu–O(hfac) of 2.3021(15) A. Thermal decomposition of 2 yields a mixture of NaCuF3, Na2CuF4 and NaF, when conducted at 230 °C in argon at ambient pressure.

Chemical reduction of a naphthylene macrocycle, [6]cyclo-2,7-naphthylene ([6]CNAP, 1), with alkali metals, Li and K, revealed the accessibility of the doubly-reduced state of 1. The macrocyclic 12- anion was isolated in different coordination environments and crystallographically characterized. The single-crystal X-ray diffraction confirmed the formation of contact-ion complexes with one Li+ and two K+ ions in THF, and a "naked" dianion in the solvent-separated ion product with K+ ions in the presence of 18-crown-6 ether. The detailed structural analysis of 12- showed that the π-conjugation over the biaryl linkages between naphthylene panels were enhanced upon two-fold reduction, which was rationally explained by theoretical calculations.

International audience; The chemical reduction of pi-conjugated bilayer nanographene 1 (C138H120) with K and Rb in the presence of 18-crown-6 affords [K+(18-crown-6)(THF)(2)][{K+(18-crown-6)}(2)(THF)(0.5)][C138H1223-] (2) and [Rb+(18-crown-6)(2)][{Rb+(18-crown-6)}(2)(C138H1223-)] (3). Whereas K+ cations are fully solvent-separated from the trianionic core thus affording a "naked" 1(.3)(-) anion, Rb+ cations are coordinated to the negatively charged layers of 1(.3)(-). According to DFT calculations, the localization of the first two electrons in the helicene moiety leads to an unprecedented site-specific hydrogenation process at the carbon atoms located on the edge of the helicene backbone. This uncommon reduction-induced site-specific hydrogenation provokes dramatic changes in the (electronic) structure of 1 as the helicene backbone becomes more compressed and twisted upon chemical reduction, which results in a clear slippage of the bilayers.

A freely soluble dianthracenoindacene derivative has been synthesized using an ‘inside-out’ Friedel–Crafts alkylation method and is the first fluorescent diacenoindacene reported. Linear fusion of the anthracenes is confirmed by X-ray diffraction studies on the neutral molecule as well as its dianion. Based on predictions from our previous studies, this is also the least antiaromatic diacenoindacene derivative yet to be prepared, which is reflected in its highly negative and irreversible reduction. With its paratropicity essentially eliminated, we posit that the molecule is no longer deactivated by a conical intersection, typical of antiaromatic molecules, and therefore fluorescence is restored. This follows the trend shown in the related dianthracenopentalenes, with the reappearance of fluorescence when the outer acene groups are extended to linearly-fused anthracene moieties.

Designed site-directed dimerization of the monoanion radicals of a π-bowl in the solid state is reported. Dibenzo[a,g]corannulene (C28 H14 ) was selected based on the asymmetry of the charge/spin localization in the C28 H14.- anion. Controlled one-electron reduction of C28 H14 with Cs metal in diglyme resulted in crystallization of a new dimer, [{Cs+ (diglyme)}2 (C28 H14 -C28 H14 )2- ] (1), as revealed by single crystal X-ray diffraction study performed in a broad range of temperatures. The C-C bond length between two C28 H14.- bowls (1.560(8) A) measured at -143 °C does not significantly change upon heating of the crystal to +67 °C. The single σ-bond character of the C-C linker is confirmed by calculations. The trans-disposition of two bowls in 1 is observed with the torsion angles around the central C-C bond of 172.3(5)° and 173.5(5)°. A systematic theoretical evaluation of dimerization pathways of C28 H14.- radicals confirmed that the trans-isomer found in 1 is energetically favored.

An X-ray diffraction study of [6]cycloparaphenylene (1), crystallized under solvent-free conditions, revealed a unique solid state structure with tight packing of individual molecules that minimizes empty internal space. The controlled chemical reduction of this highly strained nanohoop with Group 1 metals resulted in the first isolation and structural characterization of its mono- and dianions, allowing for the evaluation of core transformations for the series ranging from 10 to 11- and 12-.

Two series of aromatic compounds with perfluoroalkyl (RF ) groups of increasing length, 1,3,5,7-naphthalene(RF )4 and 1,3,5,7,9-corannulene(RF )5 , have been prepared and their electronic properties studied by low-temperature photoelectron spectroscopy (PES) (for gas-phase electron affinity measurements). These and many related compounds were also studied by DFT calculations. The data demonstrate unambiguously that the electron-withdrawing ability of RF substituents increases significantly and uniformly from CF3 to C2 F5 to n-C3 F7 to n-C4 F9 .

The first convex cesium-bound complex with a bowl-shaped carbanion, namely [{Cs+(dc-18-crown-6)}(C21H11–)] (1), has been isolated and crystallographically characterized. In the structure of 1, the cesium ion capped by dicyclohexano-18-crown-6 ether coordinates to the deprotonated five-membered ring of a sumanenyl bowl in an exo fashion with the Cs···C distances ranging from 3.315(5) to 3.609(6) A. Theoretical modeling, including a topological QTAIM approach, reveals the cumulative effect of multiple weak CH···π interactions between the cationic {Cs+(dc-18-crown-6)} moiety and the convex surface of the C21H11– anion, explaining the formation and stability of the product.

Designed synthesis of a new crystalline donor–acceptor organic hybrid has been accomplished by using two bowl-shaped polycyclic aromatic hydrocarbons (PAHs) having complementary structures and properties, namely, C20H10 and C5-C20H5(CF3)5. The X-ray structural characterization of the product, [(C20H10)·(C20H5(CF3)5)]·C6H4Cl2, revealed the formation of aligned columnar stacks of alternating C20H10 and C20H5(CF3)5 molecules with centroid-to-centroid distances of 3.658(8) and 3.787(8) A and a small bowl slip of 0.086(6) A. The tight bowl packing is accompanied by notable molecular geometry adjustments of the individual PAHs. The bowl depth increased for corannulene (Δ = +0.019 A) and decreased for sym-pentakis(trifluoromethyl)corannulene (Δ = −0.011 A), facilitating enhancement of concave–convex interactions along the stacks. The parallel alignment of one-dimensional columns is supported by multiple intermolecular interactions involving C6H4Cl2 used as the crystallization solvent, forming an infinite two-dim...