Among the many organic molecules used in metallosupramolecular assemblies are N-heterocyclic ligands. We are exploring aromatic ligands with central tetrazine rings with a focus on bptz, bmtz and bppn, which are amenable to short anion-pi contacts.  We have isoalted unprecedented metallacycles[1]-[3] in which the anions influence the self-assembly process and control the final architectures. The relatively small tetrahedral anions [ClO4]- and [BF4]-, lead to the formation of the molecular squares [M4(bptz)4(CH3CN)8][X]8 whereas the larger octahedral anions [SbF6]-, [PF6]- produce, exclusively, the molecular pentagons [M5(bptz)5(CH3CN)10][X]10. These products are also formed with the bmtz ligand. In each case, the preferred nuclearity depends on the templating ability of the anion to stabilize one molecular cage over another due to favorable anion-pi interactions. Computational studies of anion-pi interactions in these systems have led to estimates of the geometries and energies of the interactions with the results being consistent with experimental findings. Fundamental and applied aspects of the anion-pi interaction in electron-deficient pi systems will be presented.[1] Campos-Fern�ndez, C. S.; Cl�rac, R.; Koomen, J. M.; Russell, D. H.; Dunbar, K. R. J. Am. Chem. Soc. 2001  , 123, 773-774[2] Giles, I. D.; Chifotides, H. T.; Shatruk, M.; Dunbar, K. R. Chem. Commun. 2011  , 47, 12604-12606.[3] Chifotides, H. T.; Giles, I. D.; Dunbar, K. R. J. Am. Chem. Soc. 2012  , in press.

Anion-pi interactions in supramolecular interactions

245th National Meeting (2013)

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