Probing inherent helical preferences in Pt-beanpole complexes using molecular mechanics

COMP 194

Per Ola Norrby, pon@kemi.dtu.dk1, John A. Gladysz2, and Fedor A. Zhuravlev, fedorz@kemi.dtu.dk1. (1) Department of Chemistry, Technical University of Denmark, Building 201, Kemitorvet, DK-2800 Kgs. Lyngby, Denmark, (2) Institut für Organische Chemie, Friedrich-Alexander Universität Erlangen-Nürnberg, Henkestrasse 42, 91054 Erlangen, Germany
The X-ray data for square planar diplatinum “beanpole” complexes indicates a preference for helical conformation [1]. Since it is generally thought that helicity is coded at the 2D level [2] the beanpole system is unique in that it lacks any classical coding elements, such as H-bonding. The question then whether the observed helicity is due to crystal packing forces or an inherent conformational preference. Using a Pt-aware molecular mechanics force field, we find that helical conformations are preferred in vacuo. The elements contributing to the inherent helical preference are elucidated. [1] Stahl, J.; Bohling, J. C.; Bauer, E. B.; Peters, T. B.; Mohr, W.; Martín-Alvarez, J. M.; Hampel, F.; Gladysz, J. A. Angew. Chem., Int. Ed. 2002, 41, 1871. [2] Rowan, A. E.; Nolte, R. J. M. Angew. Chem., Int. Ed. 1998, 37, 6