Electronic structure studies of diradicals derived from closo-carboranes

J.M. OLIVA; D.R. ALCOBA; L. LAIN; A. TORRE

THEORETICAL CHEMISTRY ACCOUNTS

SPRINGER

Lugar: Berlin; Año: 2013 vol. 132 p. 1329 - 1329

1432-881X

Electronic structure computations have been performed on diradical systems composed of two carborane radicals CB11H12. connected through acetylene, ethylene and ethane bridge units, leading, respectively, to a linear and two trans structures. Each cage possesses one unpaired electron and the total system can thus be coupled to a singlet or a triplet state. Numerical determinations using the spin-projected method with a hybrid B3LYP functional show that these compounds have singlet ground states with low singlet-triplet energy gaps of 0.004 eV (acetylene bridge), 0.080 eV (ethylene bridge) and 0.0005 eV (ethane bridge). Spin population analyses point out a left/right localized spin distribution in the spin-projected wave function. The possibility of mapping these results onto a Heisenberg spin Hamiltonian is considered, in order to predict low-lying excited states in extended carborane chains.