1,4-Dinitrocubane and Cubane under High Pressure

Programmable synthesis of multiply arylated cubanes through C-H metalation and arylation

Cubane (C₈H₈), a cubic alkane, has long attracted attention owing to its unique 3D structure. In order to utilize the cubane scaffold widely in science and technology, a powerful method for synthesizing diverse cubane derivatives is required. Herein, we report the synthesis of mono-, di-, tri-, and tetra-arylated cubanes. Directed ortho-metalation with lithium base/alkyl zinc and subsequent palladium-catalyzed arylation enabled C–H metalation and arylation of cubane. This reaction allows the late-stage and regioselective installation of a wide range of aryl groups, realizing the first programmable synthesis of diverse multiply arylated cubanes.

Cubane has attracted attention due to its unique 3D structure. Herein, we report the programmable synthesis of multiply arylated cubanes. The developed reaction allows the late-stage and regioselective installation of aryl groups.

New Ordered Structure of Amorphous Carbon Clusters Induced by Fullerene-Cubane Reactions

As a new category of solids, crystalline materials constructed with amorphous building blocks expand the structure categorization of solids, for which designing such new structures and understanding the corresponding formation mechanisms are fundamentally important. Unlike previous reports, new amorphous carbon clusters constructed ordered carbon phases are found here by compressing C₈ H₈ /C₆₀ cocrystals, in which the highly energetic cubane (C₈ H₈ ) exhibits unusual roles as to the structure formation and transformations under pressure. The significant role of C₈ H₈ is to stabilize the boundary interactions of the highly compressed or collapsed C₆₀ clusters which preserves their long-range ordered arrangement up to 45 GPa. With increasing time at high pressure, the gradual random bonding between C₈ H₈ and carbon clusters, due to "energy release" of highly compressed cubane, leads to the loss of the ability of C₈ H₈ to stabilize the carbon cluster arrangement. Thus a transition from short-range disorder to long-range disorder (amorphization) occurs in the formed material. The spontaneous bonding reconstruction most likely results in a 3D network in the material, which can create ring cracks on diamond anvils.

Surprising Stability of Cubane under Extreme Pressure

The chemical stability of solid cubane under high-pressure was examined with in situ Raman spectroscopy and synchrotron powder X-ray diffraction (PXRD) in a diamond anvil cell (DAC) up to 60 GPa. The Raman modes associated with solid cubane were assigned by comparing experimental data with calculations based on density functional perturbation theory, and low-frequency lattice modes are reported for the first time. The equation of state of solid cubane derived from the PXRD measurements taken during compression gives a bulk modulus of 14.5(2) GPa. In contrast with previous work and chemical intuition, PXRD and Raman data indicate that solid cubane exhibits anomalously large stability under extreme pressure, despite its immensely strained 90° C-C-C bond angles.