Relativistic and cooperative effects on magnetic shieldings of dimers and clusters of halogens

SANDRA PATRICIA BLATTER; ALEJANDRO MALDONADO; GUSTAVO A. AUCAR

Munich

Congreso; 11th Triennial Congress of the World Association of Theoretical and Computational Chemists; 2017

Comité organizador local e internacional

In this presentation we show results of NMR nuclear magnetic shieldings in linear molecules containing halogen atoms XY (X, Y = F, Cl, Br, I) and the origin and magnitud of relativistic effects in such property. We analyze how large are relativistic effects on dimers as compared withsuch effects on their corresponding monomers in order to shed some light on a likely relationship among halogen bondings and relativistic effecs on magnetic shieldings. As a particular case, we studied in more details the cooperative effects in cyclic clusters of FBr n (n = 1 - 5).The whole study of magnetic properties was based on the application of the relativistic polarization propagator approach (Rel-PPA)[1] as implemented in Dirac code.[2] We also obtained the nonrelativistic values of shieldings by scaling the velocity of light (c) to infinity. This pro-cedure allows to obtain the property within both regimes, relativistic and non relativistic, using the same scheme of calculation.The bond length of monomers, XY (X, Y = F, Cl, Br, I) were taken from experimental measurements. The gauge atomic including orbitals (GIAO) was used in order to avoid the gauge dependence and ensure the basis set convergency. In the firs step we analized the magnetic shielding of halogen in monomers, and after that the same properties in dimers in order to analize the the effect of halogen bonding. The next step was to calculate magnetic shieldings in (FBr) n clusters, taken from an early study[3] and the analysis of cooperative effects that appears on one nucleus due to the presence of the other halogen atoms belonging to the cluster.Keyword: Relativistic effects; Cooperative effects; Magnetic shielding; Polarization propagators[1] G. A. Aucar, R. H. Romero, and A. F. Maldonado. Int. Rev. on Phys. Chem., 29:1, 2010.[2] DIRAC, a relativistic ab initio electronic structure program, Release DIRAC13(2013), written by L. Visscher, H. J. Aa. Jensen, R. Bast, and T. Saue. (seehttp://www.diracprogram.org).[3] R. D. Parra. Comp. Theor. Chem., 1066:47, 2015.