A novel semi‐aliphatic diamine with bulky cyclohexyl and ortho‐substituted tertiary butyl groups (4,4'‐(cyclohexylmethylene)bis(2‐(tert‐butyl)aniline), CHMBTBA) is synthesized via Mannich and rearrangement reactions of cyclohexanecarboxaldehyde and 2‐tert‐butylaniline. Afterward, several semi‐aliphatic polyimides are prepared by the high‐temperature one‐pot polymerization of CHMBTBA with various aromatic dianhydrides respectively. The resulting PIs exhibit outstanding solubility in common organic solvents (i.e., trichloromethane, etc.) and are easily processed into light color or colorless transparent films (thickness: 25 ± 1 µm) by the blade coating of polymer solution. The transmittance of all resulting films is above 86% in the visible light region (400–760 nm). Their glass transition temperatures exceed 310 °C and reach even to 374 °C (by differential scanning calorimetry). They also display low water absorption (0.29–0.87%) and good mechanical properties (tensile strength: 50.9–87.7 MPa, Young's modulus: 2.0‐2.5 GPa, elongation at break: 3.8–7.6%). Thus, they are promising potential candidates for flexible display substrates.

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Dinuclear transition-metal catalysis is a distinctive approach for cross-coupling reactions, but Rh­(I)–Rh­(III) redox catalysis has rarely been considered. Here, a dinuclear Rh­(III)–Rh­(III) redox catalytic cycle for [Rh­(coe)2Cl]2-catalyzed remote terminal arylation of activated olefins is proposed and validated by density functional theory. Calculations reveal that the catalytic cycle of terminal arylation involves phosphine-directed oxidative addition of the indole C7­(aryl)–H bond, alkene insertion, Rh-walking, and reductive elimination. Throughout the catalytic cycle, the dinuclear rhodium complex remains intact, and each of the rhodium atoms have important roles. One acts as the active catalytic center and undergoes Rh­(I)–Rh­(III) redox cycles; the other remains in the +3 oxidation state after the pre-catalytic cycle and is not directly involved in the reactions but affects the chemoselectivity by adjusting the coordination environment of the active rhodium atom. The hydroarylation regioselectivity is controlled by steric effects, which distinguish different reactive sites in the dinuclear rhodium pathway. The mononuclear rhodium catalytic cycle is unfavorable because of the endothermic monomerization process. A tether effect in the reductive elimination step also restricts generation of the δ-arylation product in the mononuclear pathway.

Density functional theory (DFT) calculations have been performed to provide mechanistic insight into the Rh/Cu co-catalyzed multicomponent annulation of indoles, diazo compounds, and α,β-unsaturated esters.

Silanes are important in chemistry and material science. The self-redistribution of HSiCl 3 is an industrial process to prepare SiH 4 , which is widely used in electronics and automobile industries. However, selective silane cross-redistribution to prepare advanced silanes is challenging. We now report an enthalpy-driven silane cross-redistribution to access bis-silanes that contain two different types of SiÀ H bonds in the same molecule. Compared with entropy-driven reactions, the enthalpy-driven reaction shows high regioselectivity, broad substrate scope (62 examples) and high atom economy. Our combined experimental and computational study indicates that the reaction proceeds through a Ni 0 -Ni II -Ni IV catalytic cycle.