Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Metal Strengthens Double Bond

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,

Robert Emmerich | Uni W¨¹rzburg
Further information:

More articles from Life Sciences:

nachricht Two decades of training students and experts in tracking infectious disease
27.11.2015 | Hochschule für Angewandte Wissenschaften Hamburg

nachricht Increased carbon dioxide enhances plankton growth, opposite of what was expected
27.11.2015 | Bigelow Laboratory for Ocean Sciences

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Climate study finds evidence of global shift in the 1980s

Planet Earth experienced a global climate shift in the late 1980s on an unprecedented scale, fuelled by anthropogenic warming and a volcanic eruption, according to new research published this week.

Scientists say that a major step change, or ‘regime shift’, in the Earth’s biophysical systems, from the upper atmosphere to the depths of the ocean and from...

Im Focus: Innovative Photovoltaics – from the Lab to the Façade

Fraunhofer ISE Demonstrates New Cell and Module Technologies on its Outer Building Façade

The Fraunhofer Institute for Solar Energy Systems ISE has installed 70 photovoltaic modules on the outer façade of one of its lab buildings. The modules were...

Im Focus: Lactate for Brain Energy

Nerve cells cover their high energy demand with glucose and lactate. Scientists of the University of Zurich now provide new support for this. They show for the first time in the intact mouse brain evidence for an exchange of lactate between different brain cells. With this study they were able to confirm a 20-year old hypothesis.

In comparison to other organs, the human brain has the highest energy requirements. The supply of energy for nerve cells and the particular role of lactic acid...

Im Focus: Laser process simulation available as app for first time

In laser material processing, the simulation of processes has made great strides over the past few years. Today, the software can predict relatively well what will happen on the workpiece. Unfortunately, it is also highly complex and requires a lot of computing time. Thanks to clever simplification, experts from Fraunhofer ILT are now able to offer the first-ever simulation software that calculates processes in real time and also runs on tablet computers and smartphones. The fast software enables users to do without expensive experiments and to find optimum process parameters even more effectively.

Before now, the reliable simulation of laser processes was a job for experts. Armed with sophisticated software packages and after many hours on computer...

Im Focus: Quantum Simulation: A Better Understanding of Magnetism

Heidelberg physicists use ultracold atoms to imitate the behaviour of electrons in a solid

Researchers at Heidelberg University have devised a new way to study the phenomenon of magnetism. Using ultracold atoms at near absolute zero, they prepared a...

All Focus news of the innovation-report >>>



Event News

Fraunhofer’s Urban Futures Conference: 2 days in the city of the future

25.11.2015 | Event News

Gluten oder nicht Gluten? Überempfindlichkeit auf Weizen kann unterschiedliche Ursachen haben

17.11.2015 | Event News

Art Collection Deutsche Börse zeigt Ausstellung „Traces of Disorder“

21.10.2015 | Event News

Latest News

Siemens to supply 126 megawatts to onshore wind power plants in Scotland

27.11.2015 | Press release

Two decades of training students and experts in tracking infectious disease

27.11.2015 | Life Sciences

Coming to a monitor near you: A defect-free, molecule-thick film

27.11.2015 | Materials Sciences

More VideoLinks >>>