title: On the Nature of Bonding in Parallel Spins in Monovalent Metal Clusters.
abstract: As we approach the Lewis model centennial, it may be timely to discuss novel bonding motifs. Accordingly, this review discusses no-pair ferromagnetic (NPFM) bonds that hold together monovalent metallic atoms using exclusively parallel spins. Thus, without any traditional electron-pair bonds, the bonding energy per atom in these clusters can reach 20 kcal mol(-1). This review describes the origins of NPFM bonding using a valence bond (VB) analysis, which shows that this bonding motif arises from bound triplet electron pairs that are delocalized over all the close neighbors of a given atom in the cluster. The VB model accounts for the tendency of NPFM clusters to assume polyhedral shapes with rather high symmetry and for the very steep rise of the bonding energy per atom. The advent of NPFM clusters offers new horizons in chemistry of highly magnetic species sensitive to magnetic and electric fields.
authors.affiliation: Institute of Chemistry, The Hebrew University, 91904 Jerusalem, Israel; email: david.danovich@mail.huji.ac.il , sason@yfaat.ch.huji.ac.il.
authors.forename: David
authors.initials: D
authors.lastname: Danovich
authors.affiliation: Institute of Chemistry, The Hebrew University, 91904 Jerusalem, Israel; email: david.danovich@mail.huji.ac.il , sason@yfaat.ch.huji.ac.il.
authors.forename: Sason
authors.initials: S
authors.lastname: Shaik
keywords: alkali metal clusters; bound triplet pairs; coinage metal clusters; no-pair ferromagnetic bonding; valence bond theory