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The substitution of fluorine atoms for oxygen atoms/hydroxyl groups has emerged as a promising strategy to enhance the physical and chemical properties of oxides/hydroxides in fluorine chemistry. However, distinguishing fluorine from oxygen/hydroxyl in the reaction products poses a significant challenge in existing characterization methods. In this study, we illustrate that terahertz (THz) spectroscopy provides a powerful tool for addressing this challenge. To this end, we investigated two fluorination reactions of boric acid, utilizing MHF2 (M=Na, C(NH2)3) as fluorine reagents. Through an interplay between THz spectroscopy and solid‐state density functional theory, we have conclusively demonstrated that fluorine atoms exclusively bind with the sp3‐boron but not with the sp2‐boron in the reaction products of Na[B(OH)3][B3O3F2(OH)2] (NaBOFH) and [C(NH2)3]2B3O3F4OH (GBF2). Based on this evidence, we have proposed a reaction pathway for the fluorinations under investigation, a process previously hindered due to structural ambiguity. This work represents a step forward in gaining a deeper understanding of the precise structures and reaction mechanisms involved in the fluorination of oxides/hydroxides, illuminated by the insights provided by THz spectroscopy. [ABSTRACT FROM AUTHOR]

The present study reports an innovative finding that alumina containing water or primary alcohol catalyzes the hydrolysis or alcoholysis, respectively, of the product formed through AlCl3‐mediated Friedel‐Crafts alkylation of methyl‐substituted benzenes and CHCl3. The former and later reactions mainly provided hydroxy‐ and alkoxy‐substituted diarylmethanes, respectively, while the reference reactions without alumina provided bisarylchloromethane. This method enables the selective syntheses of diphenylmethanol derivatives with very simple procedures, without expensive reagents and apparatuses. Furthermore, the alumina used in the reaction could be recycled by washing with water and subsequent drying. From the viewpoint of material recycling, this function is very important for the development of sustainable chemical reactions. [ABSTRACT FROM AUTHOR]

Benzenehexapyrrole-α,ω-dialdehyde, composed of a pair of formyltripyrrole units with a 1,3-phenylene linker, was metallated to give dinuclear single-stranded helicates. X-ray studies of the bis-nickel(II) complex showed a helical C2 form with a pair of helical-metal coordination planes of a 3N+O donor set. The terminal aldehyde was readily converted into the imine by optically active amines, whereby helix-sense bias was induced. Bis-nickel(II) and bis-palladium( II) complexes of the benzenehexapyrrole-α,ω-diimines were studied to show that an enantiomer pair of the helical C2 form are interchanged by slow flipping of each coordination plane and fast rotation around the C(benzene)-C(pyrrole) bond. The helical screw in the bis-nickel(II) complexes was biased to one side in more than 95% diastereoselectivity, which was achieved by using a variety of optically active amines, such as (R)-1-cyclohexylethylamine, (S)-1- phenylethylamine, l-Phe(OEt) (Phe=phenylalanine), and (R)- valinol. The nickel complexes showed much better diastereoselectivity than the corresponding palladium complexes. [ABSTRACT FROM AUTHOR]

Hexapyrrol ‐ α,ω ‐ dialdehyd mit acht Donoratomen lieferte ein Dipalladium(II) ‐ Einzelhelicat (Pd rosa, O rot, N blau). Ein schneller Wechsel zwischen den beiden Helixrichtungen wurde durch Iminbildung an den endständigen Aldehydeinheiten mit (R) ‐ (−) ‐ 1 ‐ Cyclohexylethylamin verlangsamt, was die P ‐ helicale Schraube in enormem Überschuss ergab. Dieses stabile zweikernige Einzelhelicat ändert seine chiroptischen Eigenschaften redoxgesteuert reversibel. [ABSTRACT FROM AUTHOR]

The hexapyrrole-α,ω-dicarbaldehydes 1 a and 1 b were metallated with Cu II , Ni II , and Pd II to give bimetallic complexes where a pair of 3 N+O four-coordinate metal planes are helically distorted and the central 2,2'-bipyrrole subunit adopts a cis or trans conformation. X-ray crystallographic analysis of the bisCu complex revealed a closed form with a cis-2,2'-bipyrrole subunit and an open form with a trans-2,2'-bipyrrole subunit. The bisPd complexes took a closed form both in the solid state and in solution. They are regarded as single helicates of two turns and the energy barrier for the interchange between an M helix and a P helix was remarkably influenced by the bulky 3,3'-substituent of the central 2,2'-bipyrrole subunit. Although the bisNi complexes adopt a closed form in the solid state, they exist as a homohelical open C 2 -symmetric form or a heterohelical open C i -symmetric form in solution. A theoretical study suggested that the closed form of 1 aPd was stabilized by the Pd-Pd interaction. Compound 1 aPd was reversibly oxidized by one electron at 0.14 V versus ferrocene/ferrocenium (Fc/Fc + ) and this oxidized species showed Vis/NIR absorption bands at λ=767 and 1408 nm., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)