Reshaping Rubrene by Controlled Reduction with Alkali Metals

Zabula, Alexander V.; Sumner, Natalie J.; Filatov, Alexander S.; Spisak, Sarah N.; Grigoryants, Vladimir M.; Petrukhina, Marina A.

doi:10.1002/ejic.201200164

Cited by 24 publications

(6 citation statements)

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“…The importance of alkali-metal cation−π interactions relates to their prominence in nature and materials science and thus attracts significant interest from theoretical, experimental, and crystallographic scientific communities. These interests moved over the years from small planar arenes to large and curved polyaromatic systems, ranging from fullerene fragments to fullerenes and nanotubes .…”

Section: Introductionmentioning

confidence: 99%

Tuning Binding of Rubidium Ions to Planar and Curved Negatively Charged π Surfaces

et al. 2013

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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 mode of C24H12 •–. The analysis of the X-ray structure of 5, augmented by DFT calculations, confirmed the existence of strong C–H···π interactions between the crown ether and charged surface of C24H12 •–. These interactions result in a good alignment of matching in size crown ether and coronene moieties, thereby being responsible for the formation of a hub-bound coronene product. DFT calculations were also used to follow the spin density distribution in the [Rb(18-crown-6)][C24H12] system as well as in original fragments.

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Section: Introductionmentioning

confidence: 99%

Tuning Binding of Rubidium Ions to Planar and Curved Negatively Charged π Surfaces

et al. 2013

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“…Each R 2– anion is coordinated by six K + cations (Figure b), which completes the 3D structure of K 2 R. Two of the phenyl groups of each rubrene are not involved in binding to potassium and form interlayer short contact interactions with the equivalent phenyls of rubrene in neighboring rows and layers. The coordination number of six K + cations per rubrene anion is much larger than found in rubrene salts synthesized from solution: one R 4– is only coordinated by four cations (Li + /Na + /Cs + ). , It is evident that K + ···π interactions play important roles in stabilizing the herringbone network and completing the 3D structure of the K 2 R phase, as the main π–π interactions seen in pristine rubrene are disrupted in K 2 R (shown in Figure S8, SI).…”

Section: Resultsmentioning

confidence: 98%

“…The coordination number of six K + cations per rubrene anion is much larger than found in rubrene salts synthesized from solution: one R 4− is only coordinated by four cations (Li + /Na + /Cs + ). 17,18 It is evident that K + •••π interactions play important roles in stabilizing the herringbone network and completing the 3D structure of the K 2 R phase, as the main π−π interactions seen in pristine rubrene are disrupted in K 2 R (shown in Figure S8, SI).…”

Section: Resultsmentioning

confidence: 99%

“…15 While there have been numerous studies on neutral rubrene, there are only two reports on the structure of rubrene anions from solvent synthesis, covering three different rubrene anions: R 1− (Cs + ), R 2− (Li + /Cs + ), and R 4− (Li + /Na + /Rb + /Cs + ). 17,18 Most of these anions show significant twists (R − , R 2− ) or bending (R 4− ) of the polyaromatic core and, in the case of R 4− , η 6 cation coordination by the phenyl groups. However, in all cases there are solvents present in the cation coordination sphere.…”

Section: Introductionmentioning

confidence: 99%

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Reactivity of Solid Rubrene with Potassium: Competition between Intercalation and Molecular Decomposition

et al. 2018

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We present the synthesis and characterization of the K+-intercalated rubrene (C42H28) phase, K2Rubrene (K2R), and identify the coexistence of amorphous and crystalline materials in samples where the crystalline component is phase-pure. We suggest this is characteristic of many intercalated alkali metal–polyaromatic hydrocarbon (PAH) systems, including those for which superconductivity has been claimed. The systematic investigation of K–rubrene solid-state reactions using both K and KH sources reveals a complex competition between K intercalation and the decomposition of rubrene, producing three K-intercalated compounds, namely, K2R, K(RR*), and K x R′ (where R* and R′ are rubrene decomposition derivatives C42H26 and C30H20, respectively). K2R is obtained as the major phase over a wide composition range and is accompanied by the formation of amorphous byproducts from the decomposition of rubrene. K(RR*) is synthesized as a single phase, and K x R′ is obtained only as a secondary phase to the majority K2R phase. The crystal structure of K2R was determined using high-resolution powder X-ray diffraction, revealing that the structural rearrangement from pristine rubrene creates two large voids per rubrene within the molecular layers in which K+ is incorporated. K+ cations accommodated within the large voids interact strongly with the neighboring rubrene via η6, η3, and η2 binding modes to the tetracene cores and the phenyl groups. This contrasts with other intercalated PAHs, where only a single void per PAH is created and the intercalated K+ weakly interacts with the host. The decomposition products of rubrene are also examined using solution NMR, highlighting the role of the breaking of C–Cphenyl bonds. For the crystalline decomposition derivative products K(RR*) and K x R′, a lack of definitive structural information with regard to R* and R′ prevents the crystal structures from being determined. The study illustrates the complexity in accessing solvent-free alkali metal salts of reduced PAH of the type claimed to afford superconductivity.

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“…60 Mono-, di-and tetra-anions of rubrene, (C 42 H 28 ), have been generated by reduction of the polyarene with various alkali metals. 61 A high yield synthesis of an anionic gallium(I) N-heterocyclic carbene analogue has been developed and four monomeric sodium complexes of the heterocycle have been crystallographically characterised. 62 Trimethylsilylmethylrubidium [RbCH 2 SiMe 3 ] and [CsCH 2 SiMe 3 ] have been prepared by metathesis reactions of [LiCH 2 SiMe 3 ] with rubidium or cesium t-butoxide.…”

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confidence: 99%

Alkaline and alkaline earth metals

Hill

2013

Annu. Rep. Prog. Chem., Sect. A: Inorg. Chem.

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Reshaping Rubrene by Controlled Reduction with Alkali Metals

Cited by 24 publications

References 78 publications

Tuning Binding of Rubidium Ions to Planar and Curved Negatively Charged π Surfaces

Tuning Binding of Rubidium Ions to Planar and Curved Negatively Charged π Surfaces

Reactivity of Solid Rubrene with Potassium: Competition between Intercalation and Molecular Decomposition

Alkaline and alkaline earth metals

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