TY - JOUR

T1 - Probing the aromaticity of the (HtAc)3( 2-H)6, (HtTh)3(2-H) 6 and (HtPa)3(2-H)6 clusters

AU - Ramrez-Tagle, Rodrigo

AU - Alvarado-Soto, Leonor

AU - Arratia-Perez, Ramiro

AU - Bast, Radovan

AU - Alvarez-Thon, Luis

N1 - Funding Information:
This research used resources of the National Energy Research Scientific Computing Center, which is supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. The authors are grateful for the financial support of the Grants: FONDECYT 3100048, 1110758, and 11100446, UNAB-DI-17-11/R, UNAB-DI-06-10/R, and NUCLEUS MILLENNIUM No. P07-006-F. R.B. kindly acknowledges grant FONDECYT 11100446 which funded his visit to the Universidad Andres Bello.

PY - 2011/9/14

Y1 - 2011/9/14

N2 - In this study we report about the aromaticity of the prototypical (H tAc)3(2-H)6, (HtTh) 3(2-H)6, and (HtPa) 3(2-H)6 clusters via two magnetic criteria: nucleus-independent chemical shifts (NICS) and the magnetically induced current density. All-electron density functional theory calculations were carried out using the two-component zeroth-order regular approach and the four-component Dirac-Coulomb Hamiltonian, including scalar and spin-orbit relativistic effects. Four-component current density maps and the integration of induced ring-current susceptibilities clearly show that the clusters (HtAc) 3(2-H)6 and (HtTh)3( 2-H)6 are non-aromatic whereas (HtPa) 3(2-H)6 is anti-aromatic. However, for the thorium cluster we find a discrepancy between the current density plots and the classification through the NICS index. Our results also demonstrate the increasing influence of f orbitals, on bonding and magnetic properties, with increasing atomic number in these clusters. We think that the enhanced electron mobility in (HtPa)3(2-H)6 is due the significant 5f character of its valence shell. Also the participation of f orbitals in bonding is the reason why the protactinium cluster has the shortest bond lengths of the three clusters. This study provides another example showing that the magnetically induced current density approach can give more reliable results than the NICS index.

AB - In this study we report about the aromaticity of the prototypical (H tAc)3(2-H)6, (HtTh) 3(2-H)6, and (HtPa) 3(2-H)6 clusters via two magnetic criteria: nucleus-independent chemical shifts (NICS) and the magnetically induced current density. All-electron density functional theory calculations were carried out using the two-component zeroth-order regular approach and the four-component Dirac-Coulomb Hamiltonian, including scalar and spin-orbit relativistic effects. Four-component current density maps and the integration of induced ring-current susceptibilities clearly show that the clusters (HtAc) 3(2-H)6 and (HtTh)3( 2-H)6 are non-aromatic whereas (HtPa) 3(2-H)6 is anti-aromatic. However, for the thorium cluster we find a discrepancy between the current density plots and the classification through the NICS index. Our results also demonstrate the increasing influence of f orbitals, on bonding and magnetic properties, with increasing atomic number in these clusters. We think that the enhanced electron mobility in (HtPa)3(2-H)6 is due the significant 5f character of its valence shell. Also the participation of f orbitals in bonding is the reason why the protactinium cluster has the shortest bond lengths of the three clusters. This study provides another example showing that the magnetically induced current density approach can give more reliable results than the NICS index.

UR - http://www.scopus.com/inward/record.url?scp=80052920396&partnerID=8YFLogxK

U2 - 10.1063/1.3632056

DO - 10.1063/1.3632056

M3 - Article

C2 - 21932909

AN - SCOPUS:80052920396

VL - 135

JO - Journal of Chemical Physics

JF - Journal of Chemical Physics

SN - 0021-9606

IS - 10

M1 - 104506

ER -