P?C‐Activated Bimetallic Rhodium Xantphos Complexes: Formation and Catalytic Dehydrocoupling of Amine–Boranes

{Rh(xantphos)}‐based phosphido dimers form by P C activation of xantphos (4,5‐bis(diphenylphosphino)‐9,9‐dimethylxanthene) in the presence of amine–boranes. These dimers are active dehydrocoupling catalysts, forming polymeric [H₂BNMeH]_n from H₃B⋅NMeH₂ and dimeric [H₂BNMe₂]₂ from H₃B⋅NMe₂H at low catalyst loadings (0.1 mol %). Mechanistic investigations support a dimeric active species, suggesting that bimetallic catalysis may be possible in amine–borane dehydropolymerization.     

C—H氰烷基化:导向基控制的萘酰亚胺C—H氰烷基化

氰基广泛存在药物活性分子中,且氰基可以很容易转化成酰胺、酯基、醛基以及伯胺等官能团,因此有机分子的氰烷基/甲基化反应得到有机和药学研究者的广泛关注。尽管已有合成策略可以选择性引入氰基,近年来最有效的方法是通过C—H键激活直接与乙腈或取代乙腈发生氰甲基/氰烷基化反应,因其具有高效的原子经济性以及可规避预官能团化等优点。因此,本文详细评述了自由基促进的氰甲基化、光化学催化直接氰甲基化、芳环或杂环脱氢偶联氰甲基化、导向基促进的氰甲基化、本课题组发展的荧光团(Fluorophore C—H)直接氰甲基化反应的研究进展。     

GaGa‐ und AlFe‐Mehrfachbindungen? Ein Interpretationsversuch auf der Grundlage von Kraftkonstanten

GaGa and AlFe Multiple Bonds? An Attempt of Interpretation on the Basis of Force Constants Comparison of force constant values given by DFT frequency calculations shows that GaGa‐bonds in Ga₂H₄^2– and Ga₂H₂^2– are only slightly strengthened with respect to the GaGa‐single bond in Ga₂H₆^2–. On the other hand FeAl bonds in compounds like CpAlFe(CO)₄ are interpreted as double bonds.     

Das Verhalten von Salzen in nicht w?ssrigen L?sungen

Ohne Zusammenfassung