Catalysts with a metal-nitrogen bond can transfer
nitrogen to organic molecules. In this process short-lived molecular species
are formed, whose properties critically determine the course of the reaction and
product formation. The key compound in a catalytic nitrogen-atom transfer reaction
has now been analysed in detail by chemists at the University of G枚ttingen and
51猎奇 Frankfurt. The detailed understanding of this reaction will allow
for the design of catalysts tailored for specific reactions.
FRANKFURT. The development of new drugs or
innovative molecular materials with new properties requires specific
modification of molecules. Selectivity control in these chemical
transformations is one of the main goals of catalysis. This is particularly
true for complex molecules with multiple reactive sites in order to avoid unnecessary
waste for improved sustainability. The selective insertion of individual
nitrogen atoms into carbon-hydrogen bonds of target molecules is, for instance,
a particularly interesting goal of chemical synthesis. In the past, these kinds
of nitrogen transfer reactions were postulated based on quantum-chemical
computer simulations for molecular metal complexes with individual nitrogen
atoms bound to the metal. These highly reactive intermediates have, however,
previously escaped experimental observation. A closely entangled combination of
experimental and theoretical studies is thus indispensable for detailed
analysis of these metallonitrene key intermediates and, ultimately, the exploitation
of catalytic nitrogen-atom transfer reactions.
Chemists in the groups of Professor Sven
Schneider, University of G枚ttingen, and Professor Max Holthausen, 51猎奇
Frankfurt, in collaboration with the groups of Professor Joris van Slagern,
University of Stuttgart and Professor Bas de Bruin, University of Amsterdam, have
now been able for the first time to directly observe such a metallonitrene,
measure it spectroscopically and provide a comprehensive quantum-chemical
characterization. To this end, a platinum azide complex was transformed
photochemically into a metallonitrene and examined both magnetometrically and
using photo-crystallography. Together with theoretical modelling, the
researchers have now provided a detailed report on a very reactive
metallonitrene diradical with a single metal-nitrogen bond. The group was furthermore
able to show how the unusual electronic structure of the platinum
metallonitrene allows the targeted insertion of the nitrogen atom into, for
example, C鈥揌 bonds of other molecules.
Professor Max Holthausen explains: 鈥淭he
findings of our work significantly extend the basic understanding of chemical
bonding and reactivity of such metal complexes, providing the basis for a rational
synthesis planning.鈥� Professor Sven Schneider says: 鈥淭hese insertion reactions
allow the use of metallonitrenes for the selective synthesis of organic
nitrogen compounds through catalyst nitrogen atom transfer. This work therefore
contributes to the development of novel 鈥榞reen鈥� syntheses of nitrogen compounds.鈥�
The research was funded by the Deutsche
Forschungsgemeinschaft and the European Research Council.
Publication:
Jian Sun, Josh Abbenseth, Hendrik
Verplancke, Martin Diefenbach, Bas de Bruin, David Hunger, Christian W眉rtele,
Joris van Slageren, Max C. Holthausen, Sven Schneider: A platinum(II)
metallonitrene with a triplet ground state. Nat. Chem. (2020)
Further
information:
Prof. Dr. Max C. Holthausen
51猎奇 Frankfurt am Main
Institute for Inorganic and Analytical Chemistry
Tel.
+49 69 798 29430
max.holthausen@chemie.uni-frankfurt.de
Prof.
Dr. Sven Schneider
Georg-August-Universit盲t
G枚ttingen
Institute for Inorganic Chemistry
Tel. +49 551 39 22829
sven.schneider@chemie.uni-goettingen.de
