The complexes [ReX(CO)(3)(N,N-eta(2)-4'-hydroxy-2-2',6'-2''-terpyridine)] (X = Cl,Br,I) have been synthesised and their ligand exchange reactions and fluxionality of the terpyridine unit studied. The halides are far more labile in these species than in analogous bipyridines, and it is proposed that the ligand fluxionality is involved in this reactivity. Structural studies of the family are reported along with spectroscopic studies including variable temperature NMR which is used to demonstrate a negative entropy of activation for the fluxional process. Synthesis of an analogue which is incapable of fluxional behaviour confirms the link between fluxionality and lability in these complexes.
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http://dx.doi.org/10.1039/c0dt00022a | DOI Listing |
Dalton Trans
March 2024
LIFM, IGCME, School of Chemistry, Sun Yat-Sen University, Guangzhou 510006, China.
Profound insight into the electronic structures of occasionally observed μ-P bridging phosphinines remains limited. In this work, we present the isolation and X-ray crystallographic characterization of a dimeric Rh(I) phosphinine complex exhibiting both η-P and μ-P phosphinine coordination modes. Variable temperature NMR analyses and DOSY spectrum measurement confirmed the presence of two types of fluxional phenomena in solution: η-P phosphinine bonding and dissociation, and η-P and μ-P equilibrium.
View Article and Find Full Text PDFMolecules
September 2023
Departamento de Química Inorgánica, Instituto de Síntesis Química y Catálisis Homogénea (ISQCH), Universidad de Zaragoza-CSIC, 50009 Zaragoza, Spain.
The octahydridotriborate anion plays a crucial role in the field of polyhedral boron chemistry, facilitating the synthesis of higher boranes and the preparation of diverse transition metal complexes. Among the stable forms of this anion, CsBH (or (n-CH)N)[BH] have been identified. These salts serve as valuable precursors for the synthesis of metallaboranes, wherein the triborate anion acts as a ligand coordinating to the metal center.
View Article and Find Full Text PDFChem Commun (Camb)
March 2022
Department of Molecular Chemistry and Materials Science, Weizmann Institute of Science, Rehovot 76100, Israel.
Because of the widespread use of fossil fuels and the resulting global warming, development of sustainable catalytic transformations is now more important than ever to obtain our desired fuels and building materials with the least carbon footprint and waste production. Many sustainable (de)hydrogenation reactions, including CO reduction, H carrier systems, and others, have been reported using molecular pincer complexes. A specific subset of pincer complexes containing a central acridine donor with flanking CHPR ligands, known as acridine-based PNP pincer complexes, exhibit special reactivities that are not imitable by other PNP pincer complexes such as pyridine-based or (RPCHCH)NH type ligands.
View Article and Find Full Text PDFFront Chem
February 2022
Department of Chemistry, University of Minnesota, Minneapolis, MN, United States.
Phosphate is an anion of both environmental and medical significance. The increase in phosphate levels in surface waters due primarily to run-offs from fertilized agricultural fields causes widespread eutrophication and increasingly large dead-zones. Hyperphosphatemia, a condition in which blood phosphate levels are elevated, is a primary cause of increased mortality and morbidity in chronic or advanced kidney disease.
View Article and Find Full Text PDFInorg Chem
December 2021
Department of Chemistry, Amherst College, 25 East Drive, Amherst, Massachusetts 01002, United States.
The synthesis, characterization, and polymerization kinetics of four new titanium ONN-(phenolate) alkoxide catalysts were studied. Each catalyst is fluxional at room temperature, suggesting the ligand amine arm may be labile, but adopts a geometry in solution at low temperature (223 K) and in the solid state. All catalysts are active for the ring-opening polymerization of both ε-caprolactone (CL) and -lactide (LA).
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