In one word, how would you describe your research?Dynamic. How did this research begin?During our work on dynamic processes in Pd/NHC catalytic systems, one of the key techniques we utilized was mass spectrometry.E lectrospray ionization mass spectrometry was applied to understand possible reduction pathways of the studied Pd/NHC complexes. Surprisingly,s everal NHC-free species were detected, unstabilized palladium hydride being one of them. This elusive intermediate caught our attention and we delved into the study of the observed phenomena.What is the most significant result of this study?Formation of palladium complexes, non-stabilized by direct metal bonding with strong NHC ligand, makes av ery important point. Dynamic nature of the catalytic system allows ligand-free ionic palladium complexes to be formed. These ionic species do not agglomerate while being in Pd 0 oxidation state and, notably,t hey can be isolated from the reaction mixture and recycled. What was the inspiration for this cover design?Thinking about an artwork that might describe dynamic nature of the studied system, we wanted to highlight the ease with which the catalytic system can transform. This brought us to the sketch of palladium complexes on as eesaw.I nt he image we created, alternative palladium complexes play together as friends, seesawed easily up and down by the possibility of dynamic transformations.Invited for the cover of this issue are ValentineP .A nanikov and co-workers. The image depicts the dynamic behaviour of a Pd/NHCc atalytic systemw ith easy transition from molecular to ionic complex. Read the fullt ext of the article at

The first example of an intermolecular thiolyne-ene coupling reaction is reported for the one-pot construction of CÀ S and CÀ C bonds. Thiol-yne-ene coupling opens a new dimension in building molecular complexity to access densely functionalized products. The employment of Eosin Y/DBU/MeOH photocatalytic system suppresses hydrogen atom transfer (HAT) and associative reductant upconversion (via CÀ S threeelectron σ-bond formation). Investigation of the reaction mechanism by combining online ESI-UHRMS, EPR spectroscopy, isotope labeling, determination of quantum yield, cyclic voltammetry, Stern-Volmer measurements and computational modeling revealed a unique photoredox cycle with four radical-involving stages. As a result, previously unavailable products of the thiol-yneene reaction were obtained in good yields with high selectivity. They can serve as stable precursors for synthesizing synthetically demanding activated 1,3-dienes.

A series of Pd/NHC species undergoes R–NHC coupling reaction forming catalytically active NHC-free complexes and/or colloidal Pd nanoparticles.

The product of a revealed transformation—NHC‐ethynyl coupling—was observed as a catalyst transformation pathway in the Sonogashira cross‐coupling, catalyzed by Pd/NHC complexes. The 2‐ethynylated azolium salt was isolated in individual form and fully characterized, including X‐ray analysis. A number of possible intermediates of this transformation with common formulae (NHC)nPd(C2Ph) (n=1,2) were observed and subjected to collision‐induced dissociation (CID) and infrared multiphoton dissociation (IRMPD) experiments to elucidate their structure. Measured bond dissociation energies (BDEs) and IRMPD spectra were in an excellent agreement with quantum calculations for coupling product π‐complexes with Pd0. Molecular dynamics simulations confirmed the observed multiple CID fragmentation pathways. An unconventional methodology to study catalyst evolution suggests the reported transformation to be considered in the development of new catalytic systems for alkyne functionalization reactions.

This work reveals ambident nucleophilic reactivity of imidazolium cations towards carbonyl compounds at the C2 or C4 carbene centers depending on the steric properties of the substrates and reaction conditions. Such an adaptive

The series of novel Pd/NHCF complexes were synthesized via a straightforward approach from fluorine-containing anilines. Computational and structural studies were performed to assess the effect of fluorine on the Pd–NHC bond.

An efficient strategy was developed for directing-group-free C–H functionalization of biomass-derived C6 furanic building block. Palladium-catalyzed C–H functionalization of the low-reactive C3 position was successfully performed in 2,5-diformylfuran, an important derivative of the biobased platform chemical 5-(hydroxymethyl)­furfural. The ligand-free catalytic arylation was carried out without using protecting or directing groups, which is of key importance for the studied area to achieve waste-minimized and step-economic biomass processing. The experimental results combined with density functional theory calculations revealed a reaction mechanism and indicated that the presence of the aldehyde group is essential for catalytic reaction. Enolization of the aldehyde group and Pd binding play an important role in governing the overall C–H functionalization pathway. One of the obtained arylated furanic compounds was tested as a model substrate for reduction and oxidation of carbonyl groups to highlight its versatile synthetic potential.

The Mizoroki–Heck reaction is one of the most known and best studied catalytic transformations and has provided an outstanding driving force for the development of catalysis and synthetic applications. Three out of four classical Mizoroki–Heck catalytic cycle intermediates contain Pd–C bonds and are well known and studied in detail. However, a simple palladium hydride (which is formed after the product-releasing β-H-elimination step) is a kind of elusive intermediate in the Mizoroki–Heck reaction. In the present study, we performed a combined theoretical and mass spectrometry (MS) study of palladium hydride complexes [PdX2H]− (X = Cl, Br, and I), which are reactive intermediates in the Mizoroki–Heck reaction. Static and molecular dynamic calculations revealed that these species have a T-shaped structure with a trans-arrangement of halogen atoms. Other isomers of [PdX2H]− are unstable and easily rearrange into the T-shaped form or decompose. These palladium hydride intermediates were detected by MS in precatalyst activation using NaBH4, Et3N, and a solvent molecule as reducing agents. Online MS monitoring allowed the detection of [PdX2H]− species in the course of the Mizoroki–Heck reaction.