Article
Chemistry, Physical
Yu Matsuda, Masaya Nakajima, Tetsuhiro Nemoto
Summary: Transition metal-catalyzed photoreactions have been extensively reported, but the development of ligands for these reactions is limited. This study successfully synthesized acridine-containing PNP-pincer ligands and found that the platinum complex induced photoreactions of olefins under visible light irradiation. These reactions revealed unknown reactivities of transition metals that could not be achieved with existing well-known ligands.
Article
Chemistry, Inorganic & Nuclear
Fallyn L. Kirlin, Olivia J. Borden, Marianna C. Head, Sophie E. Kelly, Anthony R. Chianese
Summary: In recent years, the metal-catalyzed hydrogenolysis of epoxides to produce alcohols has made rapid progress, with some catalysts selectively giving linear or branched products. We report the highly active nature of PNN- and PNP-ruthenium pincer complexes containing N-H functional groups for the branched-selective hydrogenolysis of epoxides. The use of isopropyl alcohol as a solvent allows for excellent yields of branched alcohol products without the need for strongly basic additives, with catalyst loadings as low as 0.03%. The selectivity for branched products is very high for epoxides containing a directly attached secondary carbon, and the branched:linear ratios for aryl-substituted epoxides vary from 2.7 to 19.0. PNP-Ru catalysts exhibit a greater preference for branched products than PNN-Ru catalysts for aryl epoxides, and substrates with electron-rich aryl substituents show a lower preference for branched products.
Article
Chemistry, Physical
Dilip K. Pandey, Eugene Khaskin, Julia R. Khusnutdinova
Summary: The widespread use of pyridine-based PNP pincer ligands has led to the concept of metal-ligand cooperation (MLC). Researchers have developed a series of methylated PNP-type pincer ligands to explore MLC blocking effects in catalysis. Methylation of PNP pincer arms has emerged as a new versatile tool to control steric hindrance and disable metal-ligand cooperative or ligand-centered reactivity. The methylation approach has been applied in hydrogenation, hydroboration, and semihydrogenation catalysis with Ru and Fe complexes.
Article
Chemistry, Physical
David A. Kuss, Markus Hoelscher, Walter Leitner
Summary: A theoretical and experimental mechanistic study was conducted on the homogeneously catalyzed CO2 hydrogenation to methanol. The results showed the significance of the formate ester intermediate and determined the turnover determining transition state. The experimental results were in good agreement with the computational model, further validating the proposed mechanism.
Article
Chemistry, Physical
Dilip K. Pandey, Eugene Khaskin, Shrinwantu Pal, Robert R. Fayzullin, Julia R. Khusnutdinova
Summary: We describe an efficient semihydrogenation of terminal alkynes using a modified tetramethylated PNP pincer Fe hydride complex. The modified complex shows different reactivity compared to a classical PNP Fe hydride complex with CH2 arms, which predominantly catalyzes terminal alkyne dimerization even in the presence of H-2. The modified PNP ligand allows for selective alkene formation, eliminating dimerization side products and minimizing overreduction.
Review
Chemistry, Multidisciplinary
Sayan Kar, David Milstein
Summary: This article discusses the unique reactivities of acridine-based pincer complexes, focusing on their synthesis, structural features, and reactivities with acids and water. Additionally, it explores the ability of these complexes to catalyze various sustainable reactions, such as the transformation of primary alcohols to primary amines using ammonia.
CHEMICAL COMMUNICATIONS
(2022)
Article
Chemistry, Inorganic & Nuclear
Marianna C. Head, Benjamin T. Joseph, Jason M. Keith, Anthony R. Chianese
Summary: The homogeneous catalysis of epoxide hydrogenolysis to give alcohols has been extensively studied. Catalyst systems have been developed for the selective formation of either branched or linear alcohol products. The proposed mechanisms of epoxide ring-opening involve cooperative C-O bond hydrogenolysis, but a new study suggests that the previously proposed bifunctional pathway is energetically inaccessible for ruthenium catalysts.
Article
Chemistry, Inorganic & Nuclear
Bin Wang, Chunying Rong, Ming Lei, Shubin Liu, Frank De Proft
Summary: Designing efficient and selective catalysts for carbon dioxide reduction is an active area of research in homogeneous catalysis. In this study, the catalytic activity of a newly reported Mn(I)-PNP-pincer catalyst with an embedded aromatic ring is investigated. The study systematically examines the catalyst's capability to yield different products and explores the importance of ligand aromaticity and steric effects on metal-ligand cooperativity. The reactivity of the catalyst is probed using conceptual density functional theory and an information-theoretic approach, leading to a novel partitioning of the reaction coordinate into three relevant regions. The results demonstrate that different properties govern the reactivity in these different regions, such as steric effects, electrophilicity/nucleophilicity, or aromaticity. The methodology and analytical tools employed in this study have the potential to be generalized and extended to other catalytic systems, offering insights towards designing improved catalysts.
INORGANIC CHEMISTRY
(2023)
Article
Chemistry, Multidisciplinary
Sylwia Kostera, Gabriele Manca, Luca Gonsalvi
Summary: Catalytic hydrogenation of CO2 to formate was achieved using the neutral, halide-free, coordinatively saturated tris(carbonyl) manganese pincer-type complex [Mn(PNP)(CO)(3)] as catalyst, DBU as base, and LiOTf as Lewis acid additive. The reaction conditions were mild (60 bar, 80°C). DFT calculations revealed that the activation of the precatalyst occurred through intermolecular, base-assisted dihydrogen heterolytic splitting.
CHEMISTRY-A EUROPEAN JOURNAL
(2023)
Article
Chemistry, Inorganic & Nuclear
Yanhong Dong, Shangqing Xie, Peng Zhang, Qingqing Fan, Xinyu Du, Hongjian Sun, Xiaoyan Li, Olaf Fuhr, Dieter Fenske
Summary: Six silyl cobalt(III) hydrides were synthesized with different substituents at the P and Si atoms, among which complex 3 exhibited excellent anti-Markovnikov regioselectivity as the best catalyst for alkene hydrosilylation. Addition of pyridine N-oxide reversed the selectivity of the reaction from anti-Markovnikov to Markovnikov addition, while maintaining high yield and excellent selectivity at a lower temperature. The proposed reaction mechanisms were based on experimental information, and the molecular structures of the complexes were determined by single crystal X-ray diffraction analysis.
INORGANIC CHEMISTRY
(2021)
Article
Chemistry, Multidisciplinary
Taichi Mitsumoto, Yuya Ashida, Kazuya Arashiba, Shogo Kuriyama, Akihito Egi, Hiromasa Tanaka, Kazunari Yoshizawa, Yoshiaki Nishibayashi
Summary: We have designed and synthesized a new molybdenum complex based on the bond dissociation free energies of N-H bonds in molybdenum-imide complexes with different substituted pyridine-based PNP-type pincer ligands. The complex exhibited excellent catalytic activity in the formation of ammonia from the reaction of dinitrogen with samarium diiodide and water under ambient conditions, with a significant improvement in catalytic performance compared to the unmodified complex.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Organic
Yinyin Wang, Xiaowan Lin, Piao Zhang, Meihua Shen, Huadong Xu, Defeng Xu
Summary: Two novel PNP pincer ligands were synthesized and evaluated in cobalt catalyzed semihydrogenation, showing significant effects on reaction rate and selectivity. The ligand L5b promoted migratory semihydrogenation of terminal alkynes, leading to E-2-alkene as main product. Overall, a method of migratory semihydrogenation was developed with the use of ligand L5b.
CHINESE JOURNAL OF ORGANIC CHEMISTRY
(2021)
Article
Chemistry, Inorganic & Nuclear
Zixing Jia, Longfei Li, Xuewen Zhang, Kan Yang, Huidong Li, Yaoming Xie, Henry F. Schaefer
Summary: In this study, a comprehensive investigation on CO2 hydroboration catalyzed by Mn pincer complexes is reported. The traditional metal-ligand cooperation mechanism is found to be inviable, and an ionic mechanism is proposed instead. The acceleration effect of bases is also unveiled. Modulating the X groups in the catalyst models can change the energy barrier of hydride transfer, and a pyridine-based Mn pincer catalyst system is designed for CO2 hydroboration in low-temperature and base-free conditions through metal-ligand cooperation.
INORGANIC CHEMISTRY
(2022)
Article
Chemistry, Inorganic & Nuclear
Sam Yruegas, Scott P. Semproni, Paul J. Chirik
Summary: The addition of excess diazoalkane to the pincer resulted in the formation of homocoupled alkene product with loss of N2. Different types of diazoalkanes generated the olefin product with other minor compounds. Multinuclear NMR spectroscopy and X-ray diffraction studies revealed the interaction between diazoalkane and cobalt, and found that the four-coordinate cobalt diazoalkane complexes promoted the formation of olefins.
Article
Chemistry, Physical
Lijun Lu, Jie Luo, David Milstein
Summary: Sulfones are important in organic synthesis and pharmaceutical chemistry. Direct alpha-alkylation of sulfones with alcohols as the reaction partners offers a promising method for their structural modification. This study reports the successful alpha-alkylation of sulfones using alcohols catalyzed by an earth-abundant manganese complex. The reaction selectivity was greatly improved by the catalyst and the amount of base used. Aromatic and aliphatic alcohols were suitable reagents for the alpha-alkylation of sulfones at low metal catalyst loading, demonstrating the practicality of the developed system.
Article
Chemistry, Multidisciplinary
Lorena De Luca, Alessandro Passera, Antonio Mezzetti
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2019)
Article
Chemistry, Multidisciplinary
Alessandro Passera, Antonio Mezzetti
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2020)
Review
Chemistry, Organic
Lorena De Luca, Antonio Mezzetti
SYNTHESIS-STUTTGART
(2020)
Article
Chemistry, Organic
Lorena De Luca, Antonio Mezzetti
JOURNAL OF ORGANIC CHEMISTRY
(2020)
Review
Chemistry, Multidisciplinary
Raffael Huber, Alessandro Passera, Antonio Mezzetti
CHEMICAL COMMUNICATIONS
(2019)