Angew. Chem. Int. Ed.

Electrochemical Migratory Cyclization of N-acylsulfonamides

Benzoxathiazine dioxide, as a bioisostere of the clinically widely used diazoxide, exhibits interesting biological activity. However, limited success has been achieved in terms of its concise and direct synthesis. We report herein a facile electrochemical migratory cyclization of N -acylsulfonamides to access a diverse array of benzoxathiazine dioxides. The inclusion of electrochemistry is crucial for realizing such a novel transformation, which is substantiated both by the experiments and density-functional-theory calculations.

Unexpected White Phosphorus (P4) Activation Modes with Silylene-Substituted o-Carboranes and Access to an Isolable 1,3-Diphospha-2,4-disilabutadiene

New types of metal-free white phosphorus (P4) activation are reported. While the phosphine-silylene-substituted dicarborane 1, CB-SiP {CB = ortho-C,C´-C2B10H10, Si = PhC(tBuN)2Si, P = P[N(tBu)CH2]2}, activates white phosphorus in a 2:1 molar ratio to yield the P5-chain containing species 2, the analogous bis(silylene)-substituted compound 3, CB-Si2, reacts with P4 in the molar ratio of 2:1 to furnish the first isolable 1,3-diphospha-2,4-disilabutadiene (Si=P-Si=P-containing) compound 4.

A Conjugated Figure-of-eight Oligoparaphenylene Nanohoop with Adaptive Cavities Derived from Cyclooctatetrathiophene Core

A fully conjugated figure-of-eight nanohoop is presented with facile synthesis. The molecule’s lemniscular skeleton features the combination of two strained oligoparaphenylene loops and a flexible cyclooctatetrathiophene core. Its rigid yet guest-adaptive cavities enable the formation of the peanut-like 1:2 host-guest complexes with C 60 or C 70 , which have been confirmed by X-ray crystallography and characterized in solution.

A Genuine Stannylone with a Monoatomic Two-Coordinate Tin(0) Atom Supported by a Bis(silylene) Ligand

The monoatomic zero-valent tin complex (stannylone) {[Si II (Xant)Si II ]Sn 0 } 5 stabilized by a bis(silylene)xanthene ligand, [Si II (Xant)Si II = PhC(N t Bu) 2 Si(Xant)Si(N t Bu) 2 CPh], and its bis-tetracarbonyliron complex {[Si II (Xant)Si II ]Sn 0 [Fe(CO) 4 ] 2 } 4 are reported. The stannylone 5 bearing a two-coordinate zero-valent tin atom is synthesized by reduction of the precursor 4 with potassium graphite.

Facile Dinitrogen and Dioxygen Cleavage by a Uranium(III) Complex: Cooperativity Between the Non‐innocent Ligand and the Uranium Center

Activation of dinitrogen (N2, 78%) and dioxygen (O2, 21%) has fascinated chemists and biochemists for decades. The industrial conversion of N2 to ammonia requires extremely high temperatures and pressure. Here we report the first example of N2 and O2 cleavage by a uranium complex, [N(CH2CH2NPiPr2)3U]2(TMEDA), under ambient conditions without an external reducing agent. The N2 triple bond breaking implies a U(III)-P(III) six-electron reduction. The hydrolysis of the N2 reduction product allows the formation of ammonia or nitrogen-containing organic compound.

Iodane‐guided ortho C‐H allylation

A metal‐free C‐H allylation strategy is described to access diverse functionalized ortho ‐allyl‐iodoarenes. The method employs hypervalent (diacetoxy)iodoarenes and proceeds through the iodane‐guided “iodonio‐Claisen” allyl transfer. The use of allylsilanes bearing electron‐withdrawing functional groups unlocks the functionalization of a broad range of substrates, including electron‐neutral and electron‐poor rings.

Bowl Inversion in an Exo‐type Supramolecule in the Solid State

Bowl inversion is a unique property of buckybowls. The polarity and assembly configuration of buckybowls are reversed after bowl inversion. So far, this unique phenomenon has been studied in solution and on surface, but not in solid state due to spatial constraint. Now a series of exo‐type supramolecular assemblies of trithiasumanene and nanographene are investigated. Tuning the electron density of the nanogaphene component was found to directly affect the binding constant of the complex.

Isolation of an Eleven‐Atom Polydentate Carbon‐Chain Chelate Obtained by Cycloaddition of a Cyclic Osmium Carbyne with an Alkyne

Carbon ligands have long played an important role in organometallic chemistry. However, previous examples of all‐carbon chelating ligands are limited. Herein, we present a novel complex with an eleven‐atom carbon chain as a polydentate chelating ligand. This species was formed by the [2+2+2] cycloaddition reaction of two equivalents of an alkyne with an osmapentalyne that contains the smallest carbyne bond angle (127.9°) ever observed. Density functional calculations revealed that electron‐donating groups play a key role in the stabilization of this polydentate carbon‐chain chelate.

Synthesis and Characterization of a Metallacyclic Framework with Three Fused Five-membered Rings

Polycyclic complexes containing a bridgehead transition metal are interesting species because the transition metal is shared by all the rings simultaneously. In this study, we present a novel osmium–bridgehead system with three fused five-membered rings. This novel framework can be viewed as a 10-atom carbon chain coordinating to the osmium center. In sharp contrast to the nonplanar organic analogue, this unique metallacycle exhibits good planarity, which was unambiguously verified by means of X-ray diffraction.

Five-Membered Cyclic Metal Carbyne: Synthesis of Osmapentalynes by the Reactions of Osmapentalene with Allene, Alkyne, and Alkene

The synthesis of small cyclic metal carbynes is challenging due to the large angle strain associated with the highly distorted nonlinear triple bonds. Herein, we report a general route for the synthesis of five-membered cyclic metal carbyne complexes, osmapentalynes, by the reactions of an osmapentalene derivative with allene, alkyne, and alkene. Experimental observations and theoretical calculations document the aromaticity in the fused five-membered rings of osmapentalynes.

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