06 Apr 08:52
by Dominic R. Willcox,
Emanuele Cocco,
Gary S. Nichol,
Stephen Thomas
Silyl-heterocycles offer a unique handle to expand and explore chemical space, reactivity, and functionality. These are limited by the lack of catalytic methods for the preparation of diverse and functionalized silyl-heterocycles. Herein the borane-catalyzed intramolecular 1,1-carboboration of silyl-alkynes has been developed for the synthesis of 2,3-dihydrosilolyl and silylcyclobut-2-enyl boronic esters.
Abstract
Silyl-heterocycles offer a unique handle to expand and explore chemical space, reactivity, and functionality. The shortage of catalytic methods for the preparation of diverse and functionalized silyl-heterocycles however limits widespread exploration and exploitation. Herein the borane-catalyzed intramolecular 1,1-carboboration of silyl-alkynes has been developed for the synthesis of 2,3-dihydrosilolyl and silylcyclobut-2-enyl boronic esters. Successful, catalytic carboboration has been achieved on a variety of functionally diverse silyl-alkynes, using a borane catalyst and transborylation-enabled turnover. Mechanistic studies, including 13C-labelling, computational studies, and single-turnover experiments, suggest a reaction pathway proceeding by 1,2-hydroboration, 1,1-carboboration, and transborylation to release the alkenyl boronic ester product and regenerate the borane catalyst.
06 Apr 08:50
by Nadeschda Geibel,
Lukas Bührmann,
Lena Albers,
Marc Schmidtmann,
Alexander Weiz,
Thomas Müller
The reactivity pattern of germaaluminocenes is determined by the dichotomy of the electron-deficient aluminum atom and the electron-rich germanium center. The analysis of the product spectra obtained from the reaction with standard reagents reveals the role of these main group sandwich complexes as synthetic equivalents of otherwise not accessible aluminagermapentafulvenes.
Abstract
Germaaluminocenes are formed by salt metathesis reactions of dipotassium germacyclopentadienediides with pentamethylcyclopentadienylaluminum dichloride. The reactivity pattern of these sandwich complexes is determined by the electrophilic central aluminum atom and by the nucleophilic dicoordinated germanium center. Surprisingly, the products formed by reactions with Lewis acids, Lewis bases, amphiphiles and compounds with polar double bonds are those expected from the reaction of a hypothetical aluminagermapentafulvene with these types of reagents. This suggests that germaaluminocenes are synthetic equivalents to these pentafulvenes.
13 Mar 08:40
by Lukas Bührmann,
Lena Albers,
Marc Schmidtmann,
Maximilian Beuße,
Thomas Müller
![Aluminagerma[5]pyramidane – Bildung und Gerüstumlagerung](https://onlinelibrary.wiley.com/cms/asset/a83e22ee-24ae-478f-9224-e1f379efd05a/ange202401467-toc-0001-m.png)
Die Synthese und Charakterisierung von η
5-Alumolkomplexen des zweiwertigen Germaniums 3 wird vorgestellt. Der Alumolkomplex 3 (R1=NCy2) befindet sich im Gleichgewicht mit seinem isomeren Aluminylen-Germolkomplex 4. Dieses Gleichgewicht zwischen den Aluminagerma[5]pyramidanen 3 und 4 ist ein interessantes Beispiel für den Austausch von zwei Heteroatomen an der apikalen Position einer pentagonalen Pyramidenstruktur unter Standardbedingungen.
Abstract
Salzmetathesereaktionen zwischen Dikaliumgermacyclopentadiendiiden und Aluminium(III)dichloriden ermöglichen die Synthese von Alumol-Halbsandwichkomplexen des zweiwertigen Germaniums oder von Aluminylen-Germol-Komplexen. Deren Molekülstrukturen und ihre delokalisierte Bindungssituation, wie sie durch Dichtefunktionalrechnungen (DFT) belegt wird, erlauben gleichermaßen ihre Beschreibung als isomere Aluminagerma[5]pyramidane mit entweder dem Germanium- oder dem Aluminiumatom in der apikalen Position der pentagonalen Pyramide. Die Produktbildung und die Selektivität der Reaktion hängen von dem dritten Substituenten des Aluminiumdichlorids ab. Arylgruppen begünstigen die Bildung von Alumolkomplexen und der Cp*-Substituent die der isomeren Germolkomplexe. Mit Aminosubstituenten am Aluminiumatom werden Mischungen beider Isomere erhalten, wobei der Austausch der Positionen der beiden Heteroatome im Pyramidan durch NMR Spektroskopie nachgewiesen wurde. Zudem können, ausgehend von Alumolkomplexen des zweiwertigen Germaniums, durch reduktive Eliminierung des Germaniums die entsprechenden Alumole erhalten werden.
12 Mar 17:41
by Jia-Ahn Pan, Artiom Skripka, Changhwan Lee, Xiao Qi, Anne L. Pham, Joshua J. Woods, Rebecca J. Abergel, P. James Schuck, Bruce E. Cohen, and Emory M. Chan
Journal of the American Chemical Society
DOI: 10.1021/jacs.3c12850
11 Mar 15:46
by Shengwen Xu, Hongjian Zhang, Jingkai Xu, Weiqun Suo, Chang-Sheng Lu, Deshuang Tu, Xingwei Guo, Jordi Poater, Miquel Solà, and Hong Yan
Journal of the American Chemical Society
DOI: 10.1021/jacs.4c00550
08 Mar 09:09
A single photonic device accommodates three different modes of operation
22 Feb 09:56
by Zihao Qiao,
Xueyan Li,
Ming Chen,
Fanshu Cao,
Zhenbo Mo
Double 1,2-carbon migration enables the isomerization of the stannagermenylidene to the germastannenylidene. Theoretical studies reveal that the isomerization process involves stepwise carboranyl group and aryl group migration. The reactivity studies demonstrate that the stannagermenylidene undergoes intriguing electron redistribution to give the germylone-stannylene adduct upon treatment with IMe4 and readily reacts with (AlCp*)4 to give the unique heteronuclear aluminyl stannagermyne.
Abstract
1,2-migration is one recurring isomerization reaction in organic chemistry. In contrast, double 1,2-migration remains rare and limited to transition-metal complexes. Herein, we describe the synthesis, characterization and reactivity of mixed heavier Sn=Ge vinylidenes. Double 1,2-carbon migration enables the isomerization of the stannagermenylidene (3) to the germastannenylidene (4). X-ray diffraction analysis and DFT calculations revealed that 3 and 4 feature a Sn=Ge double bond. The reaction of 3 with IMe4 (1,3,4,5-tetramethylimidazoline-2-ylidene) results in the electron redistribution in the Sn=Ge core to give the germylone-stannylene adduct (5). Moreover, treatment of 3 with 0.25 equiv. of (AlCp*)4 produces the heteronuclear aluminyl stannagermyne (6).
13 Feb 13:17
by Arne Merschel,
Yury Vishnevskiy,
Beate Neumann,
Georg Stammler,
Rajendra Ghadwal
KC8 reduction of 2-I with a catalytic amount the NHC (IMe4) has been shown to afford the peri-annulated compound 4 as a colorless crystalline solid. The formation of 4 suggests intramolecular insertion of the putative bis-aluminylene 3 into the C−H bonds of HCMe2 groups. Calculations predict singlet ground state for 3 while the conversion of 3 into 4 is thermodynamically favored by 61 kcal/mol.
Abstract
Carbocyclic aluminium halides [(ADC)AlX2]2 (2-X) (X=F, Cl, and I) based on an anionic dicarbene (ADC=PhC{N(Dipp)C}2, Dipp = 2,6-iPr2C6H3) framework are prepared as crystalline solids by dehydrohalogenations of the alane [(ADC)AlH2]2 (1). KC8 reduction of 2-I affords the peri-annulated Al(III) compound [(ADCH)AlH]2 (4) (ADCH=PhC{N(Dipp)C2(DippH)N}, DippH=2-iPr,6-(Me2C)C6H3)) as a colorless crystalline solid in 76 % yield. The formation of 4 suggests intramolecular insertion of the putative bis-aluminylene species [(ADC)Al]2 (3) into the methine C−H bond of HCMe2 group. Calculations predict singlet ground state for 3, while the conversion of 3 into 4 is thermodynamically favored by 61 kcal/mol. Compounds 2-F, 2-Cl, 2-I, and 4 have been characterized by NMR spectroscopy and their solid-state molecular structures have been established by single crystal X-ray diffraction.
07 Feb 10:37
by Parveen Kumar Verma, Bholanath Mahanty, Arunasis Bhattacharyya, Petr I. Matveev, Nataliya E. Borisova, Stepan N. Kalmykov, and Prasanta Kumar Mohapatra
Inorganic Chemistry
DOI: 10.1021/acs.inorgchem.3c03840
Open Access
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