Revealing Coordination Patterns in C₅-Cyclic Lithium Organics

Abstract

We kindly acknowledge funding from the DFG Priority Programme 1178, the DNRF-funded Centre of Materials Crystallography, and the doctoral programme Catalysis for Sustainable Synthesis, provided by the Land Niedersachsen. Support from the Chemetall, Frankfurt and Langelsheim, and the Volkswagenstiftung is appreciated.

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

“…[9,11,18] On the contrary, while the formation of four-fold reduced corannulene was clearly observed in the reaction mixture with Li and K metals, the assignment of the specific products in solution was problematic. [19] For example, lithium pentamethylcyclopentadienide (LiCp*) shows a peak at À12.5 ppm, [20] while shifts of 7 Li NMR signals up to À16 ppm [10b] are observed for the mixtures of corannulene and substituted fullerenes in the presence of an excess of Li metal. However, all attempts to crystallize the products from the above reaction mixtures in THF have failed.…”

“…It should be mentioned that Licontaining organometallic compounds generally show 7 Li NMR signals in the range from 0 to À20 ppm. [19] For example, lithium pentamethylcyclopentadienide (LiCp*) shows a peak at À12.5 ppm, [20] while shifts of 7 Li NMR signals up to À16 ppm [10b] are observed for the mixtures of corannulene and substituted fullerenes in the presence of an excess of Li metal. After numerous attempts and variations of experimental conditions, we have successfully crystallized the product from a diglyme/THF solution.…”

Negishi Cross-Coupling Is Compatible with a Reactive B–Cl Bond: Development of a Versatile Late-Stage Functionalization of 1,2-Azaborines and Its Application to the Synthesis of New BN Isosteres of Naphthalene and Indenyl

“…The bond distances in the six-membered azaborine ring are consistent with previously reported bond lengths for monocyclic azaborines 27 with the exception of the bridging B–C bond (bond distance highlighted in red), which is significantly longer than that found in typical monocyclic azaborine structures (1.568(3) Å vs ~1.52 Å). 27 An elongation of the bridging C–C bond in the indene/indenyl system is also observed upon deprotonation, but to a somewhat lesser extent (~1.437 Å for Li indenyl 28 vs ~1.40–1.41 Å for indene 29 ). The bridging B–C distance of 1.568 Å approaches that of a B(sp 2 )–C(sp 2 ) single bond (e.g., 1.574 Å observed for a B -Ph-substituted 1,2-azaborine 8e ).…”

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

“…It should be mentioned that Licontaining organometallic compounds generally show 7 Li NMR signals in the range from 0 to À20 ppm. [19] For example, lithium pentamethylcyclopentadienide (LiCp*) shows a peak at À12.5 ppm, [20] while shifts of 7 Li NMR signals up to À16 ppm [10b] are observed for the mixtures of corannulene and substituted fullerenes in the presence of an excess of Li metal. After numerous attempts and variations of experimental conditions, we have successfully crystallized the product from a diglyme/THF solution.…”