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Posterpreis für Ian Ridlestone

Auf dem 22. Internationalen Symposium für Fluorchemie vom 22-27July in Oxford, GB, erhielt Dr. Ian Riddlestone, Postdoc im AK Krossing, für sein Präsentation einen der begehrten Posterpreise aus einem Feld den 151 ausgestellten Postern.


Development of the Novel Perfluoropyridinoxy Based WCAs [E(OC5F4N)4]- (where E = B or Al)

Ian M. Riddlestone, Sarah Keller, Florian Kirschenmann and Ingo Krossing

Institut für Anorganische und Analytische Chemie, Albertstraße 21, University of Freiburg, Freiburg-im-Breisgau, D-79104


Weakly Coordinating Anions (WCAs) permit the preparation of cations that (almost) do not interact with their counter-ion. The evolution of modern WCAs has seen them used not only to permit the formation, isolation and structural characterisation of cationic species but evolve into specialized components in electrolytes,[1] room temperature ionic liquids[2] and catalysis.[3] One of the most weakly coordinating and versatile anions in the literature is the perfluoroalkoxyaluminate [Al(ORF)4]- (where RF = C(CF3)3).[4] Despite its high performance and versatility it remains susceptible to decomposition in the presence of extreme electrophiles and shows a tendency towards crystallographic disorder. Alternative alkoxy and aryloxy ligand residues to improve the performance of aluminate based WCAs are therefore of considerable interest.



Orienting DFT calculations identified the extreme electron withdrawing capabilities of the tetrafluoropyridoxy ligand and the extreme Fluoride Ion Affinity (FIA) of the Lewis acid Al(OC5F4N)3 (FIA = 590 kJ mol-1; c.f. 489 kJ mol-1 for SbF5). Synthetic work to prepare this Lewis acid and the corresponding borate and aluminate based WCAs [E(OC5F4N)4]- (where E = B or Al) has shown this chemistry to be dominated by the extreme Lewis acidity imparted by the tetrafluoropyrdinoxy ligand. This is highlighted by the structural characterisation of the 6-coordinate neutral aluminium species Al2(OC5F4N)4(µ-OC5F4N)2(NCMe)4 (1) (figure 1) and the 5-coordinate aluminium dianion Na2(OEt2)[Al(OC5F4N)4] (2).


 [1]       S. Seki, Y. Kobayashi, H. Miyashiro, Y. Ohno, A. Usami, Y. Mita, M. Watanabe and N. Terada, 
Chem. Commun., 2006, 2, 544. 

[2]        I. Krossing, in Comp. Inorg. Chem. II. Vol 1., Oxford Elsevier, 2013, p. 681. 

[3]        E. Y. Chen and T. J. Marks, Chem. Rev. 2000, 100, 1391. 

[4]        I.M. Riddlestone, A. Kraft, J. Schaefer and I. Krossing, Angew. Chem. Int. Ed.,   

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