Chemical syntheses of new active ingredients or functional materials are based on the use of molecular building blocks. These must be simultaneously reactive but also stable enough to enable targeted incorporation into larger molecules. A research team from the University of Göttingen and the Goethe University Frankfurt has now used the example of the diphosphorus molecule (P2) to show how such extremely unstable compounds can be used specifically for chemical reactions. The results of the study have been published in the journal CHEM.
"The pronounced differences between the elements nitrogen and phosphorus have long preoccupied chemists," says Prof. Dr. Sven Schneider from the Institute of Inorganic Chemistry at Göttingen University. "Despite their direct neighbourhood in the periodic table of the elements, their chemical and physical properties are very different." For example, nitrogen exists as a very stable diatomic gas N2 and is the main component of the Earth's atmosphere. In contrast, the analogous phosphorus compound does not exist under ordinary conditions because the P2 molecule polymerizes to form solid phosphorus modifications. However, these are difficult to use for synthetic purposes.
The scientists have now succeeded for the first time in stabilizing P2 at room temperature by binding it to two platinum atoms. "Stabilization as a metal complex enabled us to study the structure, chemical bonding, and also the reactivity of the P2 building block at normal conditions in detail using many methods," explains Prof. Dr. Max Holthausen from the Institute of Inorganic and Analytical Chemistry at Goethe University Frankfurt am Main. "Our results show that this method stabilizes the P2 very effectively, while the triple bond between the two phosphorus atoms and thus the typical reactivity is hardly changed." The principle used enables the production of new phosphorus compounds under controlled conditions - but an extension to neighboring elements of the periodic table is also conceivable. Organic phosphorus compounds are used, for example, as pharmaceuticals, plant protection agents or flame retardants.
The work was funded by the German Research Foundation (DFG) and the European Research Council (ERC).