title: Electronic Delocalization in Coordination Polymers Based on Bimetallic Carboxylates.
abstract: Computational methods (DFT at the B3LYP, PBE0 and m06 levels, MO fragments decomposition, and the broken symmetry approach) have been used to evaluate the influence of the bridging ligand (BL) on the extent of electron delocalization in coordination polymers based on diruthenium tetracarboxylates. The efficiency of three different nitrogenated axial ligands, namely pyrazine (pz), phenazine (phz), and tetrazine (tz), to mediate electron coupling between Ru2(II,II) or Ru2(II,III) centers has been estimated through four different parameters: calculated Ru-N distances, HOMO-LUMO gaps, HOMO and LUMO compositions, and magnetic coupling constants J. All these parameters pointed toward a coordination polymer based on Ru2(II,II) centers axially linked by tetrazine being the best candidate for exhibiting electron delocalization through the Ru2-BL framework. Such a compound has been synthesized and characterized; its vis-NIR spectrum exhibited the predicted features, mainly an intense low-energy MLCT band, assigned to the expected Ru2(II,II) → tz process associated with electron delocalization.
authors.affiliation: INQUIMAE, Departamento de Química Inorgánica, Analítica y Química Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón II, Ciudad Universitaria, C1428EHA Buenos Aires, Argentina.
authors.forename: María Ana
authors.initials: MA
authors.lastname: Castro
authors.affiliation: Quantum Theory Project, University of Florida, Gainesville, Florida 32611, United States.
authors.forename: Adrián E
authors.initials: AE
authors.lastname: Roitberg
authors.affiliation: INQUIMAE, Departamento de Química Inorgánica, Analítica y Química Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón II, Ciudad Universitaria, C1428EHA Buenos Aires, Argentina.
authors.forename: Fabio D
authors.initials: FD
authors.lastname: Cukiernik