title: Bound Triplet Pairs in the Highest Spin States of Coinage Metal Clusters.
abstract: The work discusses bonding in coinage metal clusters, (n+1)Mn (M = Cu, Ag, Au), that have maximum spin without a single electron pair. It is shown that the bonding energy per atom, De/n, exhibits a strong nonadditive behavior; it grows rapidly with the cluster size and converges to values as large as 16-19 kcal/mol for Au and Cu. A valence bond (VB) analysis shows that this no-pair ferromagnetic bonding arises from bound triplet electron pairs that spread over all the close neighbors of a given atom in the clusters. The bound triplet pair owes its stabilization to the resonance energy provided by the mixing of the local ionic configurations, (3)M(↑↑)(- )M(+) and M(+ 3)M(↑↑)(-), and by the various excited covalent configurations (involving pz and dz(2) atomic orbitals) into the fundamental covalent structure (3)(M↑↑M) with a s(1)s(1) electronic configuration. The VB model shows that a weak interaction in the dimer can become a remarkably strong binding force that holds together monovalent atoms without a single electron pair.
authors.affiliation: The Institute of Chemistry and The Lise-Meitner Minerva Center for Computational Quantum Chemistry, The Hebrew University, Jerusalem 91904, Israel.
authors.forename: David
authors.initials: D
authors.lastname: Danovich
authors.affiliation: The Institute of Chemistry and The Lise-Meitner Minerva Center for Computational Quantum Chemistry, The Hebrew University, Jerusalem 91904, Israel.
authors.forename: Sason
authors.initials: S
authors.lastname: Shaik