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1. The Application of Transition Metal Sulfide Nanomaterials and Their Composite Nanomaterials in the Electrocatalytic Reduction of CO2: A Review

   https://doi.org/10.3390/app13053023  

   Parsons, Jason; Alotaibi, Mataz (March 2023, Applied Sciences)

   Electrocatalysis has become an important topic in various areas of research, including chemical catalysis, environmental research, and chemical engineering. There have been a multitude of different catalysts used in the electrocatalytic reduction of CO2, which include large classes of materials such as transition metal oxide nanoparticles (TMO), transition metal nanoparticles (TMNp), carbon-based nanomaterials, and transition metal sulfides (TMS), as well as porphyrins and phthalocyanine molecules. This review is focused on the CO2 reduction reaction (CO2RR) and the main products produced using TMS nanomaterials. The main reaction products of the CO2RR include carbon monoxide (CO), formate/formic acid (HCOO−/HCOOH), methanol (CH3OH), ethanol (CH3CH2OH), methane (CH4), and ethene (C2H4). The products of the CO2RR have been linked to the type of transition metal–sulfide catalyst used in the reaction. The TMS has been shown to control the intermediate products and thus the reaction pathway. Both experimental and computational methods have been utilized to determine the CO2 binding and chemically reduced intermediates, which drive the reaction pathways for the CO2RR and are discussed in this review. 

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2. Recent Advances in Metal‐Catalyzed Functionalization of Indoles

   https://doi.org/10.1002/adsc.202100116  

   Urbina, Kelvin; Tresp, David; Sipps, Karli; Szostak, Michal (April 2021, Advanced Synthesis & Catalysis)

   Abstract Indole is one of the most important heterocycles in organic synthesis, natural products, and drug discovery. Recently, tremendous advances in the selective functionalization of indoles have been reported. Although the most important advances have been powered by transition metal catalysis, exceedingly useful methods in the absence of transition metals have also been reported. In this review, we provide an overview of functionalization reactions of indoles that have been published in the last years with a focus on the most recent advances, aims, and future trends. The review is organized by the positional selectivity and type of methods used for functionalization. In particular, we discuss major advances in transition‐metal‐catalyzed C−H functionalization at the classical C2/C3 positions, transition‐metal‐catalyzed C−H functionalization at the remote C4/C7 positions, transition‐metal‐catalyzed cross‐coupling, and transition‐metal‐free functionalization. magnified image 

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3. Non-Classical Amide Bond Formation: Transamidation and Amidation of Activated Amides and Esters by Selective N–C/O–C Cleavage

   https://doi.org/10.1055/s-0040-1707101  

   Li, Guangchen; Szostak, Michal (January 2020, Synthesis)

   In the past several years, tremendous advances have been made in non-classical routes for amide bond formation that involve transamidation and amidation reactions of activated amides and esters. These new methods enable the formation of extremely valuable amide bonds via transition-metal- catalyzed, transition-metal-free or metal-free pathways by exploiting chemoselective acyl C–X (X = N, O) cleavage under mild conditions. In a broadest sense, these reactions overcome the formidable challenge of activating C–N/C–O bonds of amides or esters by rationally tackling nN→π*C=O delocalization in amides and nO→π*C=O donation in esters. In this account, we summarize the recent remarkable advances in the development of new methods for the synthesis of amides with a focus on (1) transition-metal/NHC- catalyzed C–N/C–O bond activation, (2) transition-metal-free highly selective cleavage of C–N/C–O bonds, (3) the development of new acyl-transfer reagents, and (4) other emerging methods. 

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4. Re©B8– and Re©B9–: New Members of the Transition-Metal-Centered Borometallic Molecular Wheel Family

   https://doi.org/doi: 10.1021/acs.jpca.9b03942  

   T. T. Chen, W. L. (October 2019, The journal of physical chemistry. A)

   Transition-metal-centered monocyclic boron wheel clusters (M©Bnq) represent a family of interesting borometallic compounds with double aromaticity. A variety of early and late transition metal atoms have been found to form such structures with high symmetries and various Bn ring sizes. Here we report a combined photoelectron spectroscopy and quantum chemistry theoretical study of two M©Bn– clusters from the middle of the transition metal series: Re©B8– and Re©B9–. Global minimum structure searches reveal that ReB8– adopts a pseudo-C8v structure, while ReB9– is a perfect-planar D9h molecular wheel. Chemical bonding analyses show that both clusters exhibit  and  double aromaticity and obey the electronic design principle for metal-centered borometallic molecular wheels. The central Re atom are found to possess unusually low oxidation states of +I in Re©B8– and +II in Re©B9–, i.e. the Re atom behaves similarly to late transition-metal elements (Ru, Fe, Co, Rh, Ir) in the M©Bn– molecular wheels. These two clusters become new members of the family of transition-metal-centered monocyclic borometallic molecular wheels, which may be viable for chemical syntheses with appropriate ligands. 

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5. Statistical analysis of C–H activation by oxo complexes supports diverse thermodynamic control over reactivity

   https://doi.org/10.1039/D0SC06058E  

   Schneider, Joseph E.; Goetz, McKenna K.; Anderson, John S. (March 2021, Chemical Science)

   null (Ed.)

   Transition metal oxo species are key intermediates for the activation of strong C–H bonds. As such, there has been interest in understanding which structural or electronic parameters of metal oxo complexes determine their reactivity. Factors such as ground state thermodynamics, spin state, steric environment, oxygen radical character, and asynchronicity have all been cited as key contributors, yet there is no consensus on when each of these parameters is significant or the relative magnitude of their effects. Herein, we present a thorough statistical analysis of parameters that have been proposed to influence transition metal oxo mediated C–H activation. We used density functional theory (DFT) to compute parameters for transition metal oxo complexes and analyzed their ability to explain and predict an extensive data set of experimentally determined reaction barriers. We found that, in general, only thermodynamic parameters play a statistically significant role. Notably, however, there are independent and significant contributions from the oxidation potential and basicity of the oxo complexes which suggest a more complicated thermodynamic picture than what has been shown previously. 

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