Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Metal Strengthens Double Bond

10.12.2012
Professor Holger Braunschweig and his team come up with stunning new discoveries in chemistry with great regularity. This time, the Würzburg researchers turn an established model describing catalytic processes on its head.

Be it margarine, chemical fertilizers or plastic cups: The chemical principle of catalysis plays an important role in the production of various products. In the production process, a so-called catalyst enables certain reactions to proceed. Catalysts are indispensable for hardening vegetable oils into margarine or for producing polyethylene and other plastics.

Take the example of margarine: In order to create spreadable fat from liquid vegetable oil, you need to break bonds in hydrogen molecules. This is where a metallic catalyst comes in. Its metal atom pushes electrons into the bonds, destabilizing them in the process, so that they are ready for the desired reaction.

Established model turned on its head

A metal donates electrons, thereby weakening chemical bonds: This effect – known as the "Dewar-Chatt-Duncanson model" – has been known to chemists since 1953. However, the model must now be supplemented, having been turned on its head by chemists of the University of Würzburg.

The new insight: The electrons of a metal can also strengthen a chemical bond – at least in the case of a double bond between two boron atoms. This is reported in the journal "Nature Chemistry" by researchers of Professor Holger Braunschweig's study group.

Theory experimentally confirmed

A double bond between two boron atoms can accommodate exactly two additional electrons. Chemists speak in this context of a "free II-orbital". If you fill this space, the bond should become stronger: This is the assumption that the Würzburg chemists Dr. Rian Dewhurst and Dr. Alfredo Vargas started from. They modeled their idea on the computer and found it confirmed – purely theoretically at first.

The next step was to confirm the theory by means of an experiment. Within the study group, the researchers found a molecule that was ideally suited for this purpose: a so-called platinum diboranyl complex. This molecule had been synthesized in a sophisticated process by Alexander Damme when working on his doctoral thesis.

Boron-boron double bond plus platinum

The centerpiece of the complex consists of two boron atoms that are linked to each other by a single bond in close proximity to a platinum atom. Damme devised the following procedure: He forced additional electrons on the complex, thus producing a boron-boron double bond.

According to the established model, this double bond should have been weaker than a "normal" boron-boron double bond due to the influence of the platinum metal. In actual fact, however, the bond even proved to be stronger. This was shown in a single crystal X-ray diffraction analysis of the material. This method allows you to determine how far the atoms of a molecule are apart from each other. The closer they are together, the stronger their bond will be. The Würzburg chemists found out that two boron atoms in a double bond come significantly closer together in the presence of platinum than they do without the metal.

New knowledge for textbooks

What are the consequences of this discovery? The everyday practice in chemical laboratories and industrial processes won't be affected for now. But the chemistry textbooks need to be supplemented. To be sure, the "Dewar-Chatt-Duncanson model" has not yet become obsolete; it remains applicable to carbon compounds. But it needs to be substantially extended now. You never know – maybe a model by the name of "Braunschweig-Damme-Dewhurst-Vargas" will be added.

“Bond-strengthening II backdonation in a transition-metal II-diborene complex”, Holger Braunschweig, Alexander Damme, Rian D. Dewhurst, and Alfredo Vargas, Nature Chemistry, 2012 Dec 9, DOI: 10.1038/NCHEM.1520

Contact person

Prof. Dr. Holger Braunschweig, Institute for Inorganic Chemistry of the University of Würzburg, T +49 (0)931 31-85260, h.braunschweig@uni-wuerzburg.de

Robert Emmerich | Uni W¨¹rzburg
Further information:
http://www.uni-wuerzburg.de

More articles from Life Sciences:

nachricht Researchers develop eco-friendly, 4-in-1 catalyst
25.04.2017 | Brown University

nachricht Transfecting cells gently – the LZH presents a GNOME prototype at the Labvolution 2017
25.04.2017 | Laser Zentrum Hannover e.V.

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

7th International Conference on Crystalline Silicon Photovoltaics in Freiburg on April 3-5, 2017

03.04.2017 | Event News

 
Latest News

NASA's Fermi catches gamma-ray flashes from tropical storms

25.04.2017 | Physics and Astronomy

Researchers invent process to make sustainable rubber, plastics

25.04.2017 | Materials Sciences

Transfecting cells gently – the LZH presents a GNOME prototype at the Labvolution 2017

25.04.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>