title: Anti-electrostatic hydrogen bonds.
abstract: Ab initio and hybrid density functional techniques were employed to characterize a surprising new class of H-bonded complexes between ions of like charge. Representative H-bonded complexes of both anion-anion and cation-cation type exhibit appreciable kinetic stability and the characteristic theoretical, structural, and spectroscopic signatures of hydrogen bonding, despite the powerful opposition of Coulomb electrostatic forces. All such "anti-electrostatic" H-bond (AEHB) species confirm the dominance of resonance-type covalency ("charge transfer") interactions over the inessential (secondary or opposing) "ionic" or "dipole-dipole" forces that are often presumed to be essential for numerical modeling or conceptual explanation of the H-bonding phenomenon.
authors.affiliation: Theoretical Chemistry Institute and Department of Chemistry, University of Wisconsin, Madison WI 53706 (USA). weinhold@chem.wisc.edu.
authors.forename: Frank
authors.initials: F
authors.lastname: Weinhold
authors.forename: Roger A
authors.initials: RA
authors.lastname: Klein
keywords: bond theory; computational chemistry; hydrogen bonds; natural bond orbitals; resonance