Scientists in Russian Academy of Sciences, Moscow have studied the mechanism of gold-mediated transformation of acetylenic molecules.
A recently published study by Ananikov and co-workers gives a vivid example of unusual chemical reactivity found in the reactions with organogold complexes. Using the complex of modern physical methods joined with computational studies, the authors proposed reaction mechanism, where a molecule of acetic acid serves as a proton shuttle, transferring the hydrogen atom between the reaction centers.
Being found mostly in the native state, gold is one of the oldest elements known to man. The affection to gold was determined by it's unusual properties – heft, shine and ability to withstand oxidation and corrosion. The combination of properties determined gold use in the jewelry and as a coinage metal.
The ancient alchemists working with gold were struggled by utmost chemical resistance of this element – it did not react with concentrated acids or alkali solutions even at high temperatures. Actually, it is the chemical inertness that makes gold to appear in a native form and not as a part of a mineral.
Later analysis established that gold compounds can not only compete with traditional nickel and palladium-based catalysts in the common reactions, but to surpass them. Besides that, gold compounds often demonstrated principally novel types of reactivity compared to well-established catalysts. This allowed chemists to discover a bunch of new chemical reactions and predetermined a fascinating boom in gold catalysis that we have observed in the recent years.
Professor Ananikov and co-workers introduced gold into well-known catalytic system which led to dramatic change of the reactivity and furnished the formation of novel gold-containing complexes. The complexes appeared to be air stable and were isolated in the individual state. A single crystal X-Ray diffraction study ascertained the existence of unique structural motif in the molecule, which can not be explained within conventional mechanistic framework.
The study was carried out using both theoretical and experimental approaches. Dedicated labeling of the reagents allowed observation of molecular re-organizations. Variation of reaction conditions helped to estimate key factors governing the discovered transformation.
In addition, computational study of the reaction provided the models of certain intermediate steps, which were invisible for experimental investigation. The theoretical data obtained was in excellent agreement with experiment, proposing the reaction mechanism, where a molecule of acetic acid serves as a proton shuttle, transferring the hydrogen atom between the reaction centers.
The belief of gold inactivity towards chemical transformations resulted in the fact, that organometallic chemistry of gold was developed significantly later compared to other coinage metals (like silver, nickel or copper). Today, our goal is to “introduce gold catalysis as a valuable practical tool in fine organic chemistry, competitive with other transition metal catalysts”, says Prof. Ananikov.
S. S. Zalesskiy, V. N. Khrustalev, A. Yu. Kostukovich, and V. P. Ananikov, "Carboxylic Group-Assisted Proton Transfer in Gold-Mediated Thiolation of Alkynes", Organometallics, 2015, Article ASAP. DOI: 10.1021/acs.organomet.5b00210
Researchers identify potentially druggable mutant p53 proteins that promote cancer growth
09.12.2016 | Cold Spring Harbor Laboratory
Plant-based substance boosts eyelash growth
09.12.2016 | Fraunhofer-Institut für Angewandte Polymerforschung IAP
Physicists of the University of Würzburg have made an astonishing discovery in a specific type of topological insulators. The effect is due to the structure of the materials used. The researchers have now published their work in the journal Science.
Topological insulators are currently the hot topic in physics according to the newspaper Neue Zürcher Zeitung. Only a few weeks ago, their importance was...
In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.
Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...
Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
09.12.2016 | Life Sciences
09.12.2016 | Ecology, The Environment and Conservation
09.12.2016 | Health and Medicine