Publications de Zhaowen Dong | EPFL Graph Search

Synthesis and Reactivity of an Anionic Diazoolefin

Kay Severin, Rosario Scopelliti, Farzaneh Fadaei Tirani, Zhaowen Dong, Bastiaan Kooij

Bent (hetero)allenes such as carbodicarbenes and carbodiphosphoranes can act as neutral C-donor ligands, and diverse applications in coordination chemistry have been reported. N-Heterocyclic diazoolefins are heterocumulenes, which can function in a similar ...

Wiley-VCH Verlag GmbH2023

Head‐to‐Tail Dimerization of N‐Heterocyclic Diazoolefins

Andrzej Sienkiewicz, Kay Severin, Rosario Scopelliti, Farzaneh Fadaei Tirani, Paul Varava, Zhaowen Dong, Anastasia Gitlina, Wolfram Feuerstein, Tak Hin Wong

The head-to-tail dimerization of N-heterocyclic diazoolefins is described. The products of these formal (3+3) cycloaddition reactions are strongly reducing quinoidal tetrazines. Oxidation of the tetrazines occurs in a stepwise fashion, and we were able to ...

Wiley-VCH Verlag GmbH2023

A Mesoionic Diselenolene Anion and the Corresponding Radical Dianion

Andrzej Sienkiewicz, Kay Severin, Rosario Scopelliti, Farzaneh Fadaei Tirani, Abdusalom Suleymanov, Cesare Berton, Zhaowen Dong

Dichalcogenolenes are archetypal redox non-innocent ligands with numerous applications. Herein, we describe a diselenolene ligand with fundamentally different electronic properties. By selenation of a C2-protected imidazolium salt, we have prepared a mesoi ...

2022

Vanadium complexes with N-heterocyclic vinylidene ligands

Kay Severin, Rosario Scopelliti, Farzaneh Fadaei Tirani, Paul Varava, Zhaowen Dong, Bastiaan Kooij, Laura Piveteau

The preparation and the structural characterization of vanadium complexes with terminal and bridging N-heterocyclic vinylidene ligands is reported. The synthesis of the complexes was enabled by utilization of diazoolefins as ligand precursors. Structural d ...

Royal Society of Chemistry2022

Multimodal host–guest complexation for efficient and stable perovskite photovoltaics

Michael Graetzel, Shaik Mohammed Zakeeruddin, Ursula Röthlisberger, Ulf Anders Hagfeldt, Marko Mladenovic, David Lyndon Emsley, Farzaneh Jahanbakhshi, Paramvir Ahlawat, Zaiwei Wang, Jovana Milic, Dan Ren, Aditya Mishra, Felix Thomas Eickemeyer, Hong Zhang, Zhaowen Dong, Jinming Guo, Michael Allan Hope, Anurag Krishna, Olivier Ouellette, Tzu-Sen Su, Zhiwen Zhou

Formamidinium lead iodide perovskites are promising light-harvesting materials, yet stabilizing them under operating conditions without compromising optimal optoelectronic properties remains challenging. We report a multimodal host–guest complexation strat ...

Nature Research2021

Construction of Functional Superhydrophobic Biochars as Hydrogen Transfer Catalysts for Dehydrogenation of N-Heterocycles

Feng Zhou, Zhaowen Dong

To endow metal-free materials with the high catalytic activity that is typically featured by a metal-based catalyst is yet a constant pursuit in the field of catalytic chemistry. In this work, novel functional biochars (DCNs) were prepared from wheat straw ...

AMER CHEMICAL SOC2021

Isolation and characterization of diazoolefins

Kay Severin, Rosario Scopelliti, Farzaneh Fadaei Tirani, Paul Varava, Zhaowen Dong

Diazoolefins tend to be highly reactive compounds that rapidly lose dinitrogen. So far, most experimental evidence for diazoolefins is indirect, via trapping experiments. Here we show that diazoolefins are observed to form in reactions of N-heterocyclic ol ...

2021

Tuning the π‐Accepting Properties of Mesoionic Carbenes: A Combined Computational and Experimental Study

Andrzej Sienkiewicz, Kay Severin, Rosario Scopelliti, Anne-Clémence Corminboeuf, Farzaneh Fadaei Tirani, Jacob Terence Blaskovits, Zhaowen Dong

Mesoionic imidazolylidenes are recognized as excellent electron-donating ligands in organometallic and main group chemistry. However, these carbene ligands typically show poor π-accepting properties. We have performed a computational analysis of 71 mesoion ...

2021

Three-membered cyclic digermylenes stabilised by an N-heterocyclic carbene dagger

Zhaowen Dong

Treatment of potassium salts of silole dianions with donor stabilised germanium dichlorides gave the anticipated silagermafulvenylidenes R2Si = Ge(Do) (R2Si = 1-silacyclopentadiendiyl, Do = N-heterocyclic carbene (NHC)) only as transient intermediates in a ...

2021

Triazene-Activated Donor–Acceptor Cyclopropanes: Ring-Opening and (3 + 2) Annulation Reactions

Kay Severin, Rosario Scopelliti, Jérôme Waser, Farzaneh Fadaei Tirani, Abdusalom Suleymanov, Bastian Antoine Rodolphe Claude Muriel, Eliott Hugo Joran Le Du, Zhaowen Dong

Donor–acceptor cyclopropanes substituted with 3,3-dialkyltriazenyl groups are described herein. The strong electron-donating character of the triazene renders the cyclopropanes highly reactive, allowing for catalyst-free ring-opening reactions with methano ...

2020

SET processes in Lewis acid–base reactions: the tritylation of N-heterocyclic carbenes

Andrzej Sienkiewicz, Kay Severin, Rosario Scopelliti, Cristian Pezzato, Farzaneh Fadaei Tirani, Zhaowen Dong

Reactions between N-heterocyclic carbenes (NHCs) and the trityl cation, [Ph3C]+, give covalent adducts of type [NHC–CPh3]+ and/or [NHC–C6H5–CPh2]+. EPR spectroscopy, UV-Vis analyses, and trapping experiments imply that adduct formation involves carbene rad ...

2020