title: σ-Aromaticity in polyhydride complexes of Ru, Ir, Os, and Pt.
abstract: Transition-metal hydrides represent a unique class of compounds, which are essential for catalysis, organic synthesis, and hydrogen storage. In this work we study IrH5(PPh3)2, (RuH5(P(i)Pr3)2)(-), (OsH5(P(i)Pr3)2)(-), and OsH4(PPhMe2)3 polyhydride complexes, inspired by the recent discovery of the σ-aromatic PtZnH5(-) cluster anion. The distinctive feature of these molecules is that, like in the PtZnH5(-) cluster, the metal is five-fold coordinated in-plane, and holds additional ligands at the axial positions. This work shows that the unusual coordination in these compounds indeed can be explained by σ-aromaticity in the pentagonal arrangement, stabilized by the atomic orbitals on the metal. Based on this newly elucidated bonding principle, we additionally propose a new family of polyhydrides that display a uniquely high coordination. We also report the first indications of how aromaticity may impact the reactivity of these molecules.
authors.affiliation: Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095-1569, USA. ana@chem.ucla.edu.
authors.forename: Elisa
authors.initials: E
authors.lastname: Jimenez-Izal
authors.affiliation: Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095-1569, USA. ana@chem.ucla.edu and California NanoSystems Institute, University of California, Los Angeles, CA 90095-1569, USA.
authors.forename: Anastassia N
authors.initials: AN
authors.lastname: Alexandrova