Gas-phase proton affinities (PAs) and hydride affinities (HAs) of organic bases possessing an allene moiety and substituted with methyl, dimethylamino, cyano, and vinyl substituents were examined with the B3LYP/6-311+G(2df,p)//B3LYP/6-31G(d) model. It was shown that a number of superbases and hyperbases can be obtained, as well as the potent hydride sponges. Methyl or dimethylamino substituents increased the proton affinity of the parent molecule, and the cyano substituents increased its hydride affinity. When the vinyl substituents are placed on allene, both the hydride and the proton affinities increased. A disubstituted allene with two dimethylamino groups is the smallest studied superbase, whereas the allene tetrasubstituted with four vinyl groups gives the smallest superbase possessing only alkene substituents. By introducing the vinyl group as a repeating subunit, one can obtain dendritic structures with the investigated substituents determining its properties. By changing the dimethylamino with the cyano group, a dendrimeric molecule can change from a hyperbase with a proton affinity of 324.6 kcal mol to a very strong hydride ion acceptor with a hydride affinity of 205.4 kcal mol, while possessing the same proton or hydride ion attachment site.
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http://dx.doi.org/10.1021/acs.joc.8b02641 | DOI Listing |
J Am Chem Soc
January 2025
Institut für Chemie, Technische Universität Chemnitz, Straße der Nationen 62, 09111 Chemnitz, Germany.
We present a bifunctional catalyst consisting of a copper(I)/N-heterocyclic carbene and an organocatalytic guanidine moiety that enables, for the first time, a copper(I)-catalyzed reduction of amides with H as the terminal reducing agent. The guanidine allows for reactivity tuning of the originally weakly nucleophilic copper(I) hydrides - formed in situ - to be able to react with difficult-to-reduce amides. Additionally, the guanidine moiety is key for the selective recognition of "privileged" amides based on simple and readily available heterocycles in the presence of other amides within one molecule, giving rise to hitherto unknown site-selective catalytic amide hydrogenation.
View Article and Find Full Text PDFChempluschem
January 2025
Tohoku University, Institute of Multidisciplinary Research for Advanced Materials, 2-1-1 Katahira, Aoba-ku, 9808577, Sendai, JAPAN.
Organic hydrides can store hydrogen via chemical bonding under ambient conditions, enabling the safe storage and transportation of hydrogen gas using the same infrastructure for gasoline. However, in previous research, most organic hydrides have been produced from petroleum, and therefore replacing them with earth-abundant or renewable compounds is essential to ensure sustainability. This study demonstrates dihydrolevoglucosenone (CyreneTM), which is a biodegradable liquid ketone that is produced directly from biomass without pretreatments on an industrial scale, as a new renewable organic hydride.
View Article and Find Full Text PDFACS Omega
December 2024
Departamento de Química, Instituto Tecnológico de Aeronáutica, São José dos Campos, São Paulo CEP 12228-900, Brazil.
The five-coordinate complex [RuCl(PNP)] () was synthesized from the binuclear [RuCl(-cym)] with a PNP-type ligand (PNP = 3,6-di--butyl-1,8-bis(dipropylphosphino)methyl)-9-carbazole - (Cbzdiphos )H) in a toluene solution, within 20 h at 110 °C, producing a green solid, which was precipitated with a 1/1 mixture of - pentane/HMDSO. The complex was characterized by NMR-H, C, and P{H}, mass spectroscopy-LIFDI, FTIR, UV/vis spectroscopy, and cyclic voltammetry, as well as a description of the optimized structure by DFT calculation. The reactivity of was investigated in the presence of potassium triethylborohydride (KBEtH, in THF solution of 1.
View Article and Find Full Text PDFJ Org Chem
January 2025
Centre for Organometallic Chemistry, School of Chemistry, Bharathidasan University, Tiruchirappalli 620 024, India.
A streamlined strategy for the one-pot synthesis of isoxazolone analogues has been developed through an acceptorless dehydrogenative annulation (ADA) pathway by employing new Ru(II) hydride complexes as effective catalysts. New Ru(II) complexes () tailored with N̂O chelating carbazolone benzhydrazone ligands were synthesized and their formation was confirmed using analytical and spectral techniques including FT-IR and NMR. The structural configuration of the complexes featuring an octahedral geometry around the Ru(II) ion was precisely determined by single-crystal X-ray diffraction analysis.
View Article and Find Full Text PDFHeliyon
December 2024
Department of Earth and Environmental Sciences and Williamson Research Centre for Molecular Environmental Sciences, School of Natural Sciences, Faculty of Science and Engineering, The University of Manchester, Manchester, M13 9PL, United Kingdom.
Myanmar is a major rice exporter. Rice is an important source of nourishment for its population. However, rice can be contaminated with toxic elements, including arsenic, long-term exposure to which has been linked to several illnesses, including cancer.
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