Thioarsenides: A case for long-range Lewis acid-base-directed van der Waals interactions

G. V. Gibbs, A. F. Wallace, R. T. Downs, N. L. Ross, D. F. Cox, K. M. Rosso

Research output: Contribution to journalArticlepeer-review

12 Scopus citations


Electron density distributions, bond paths, Laplacian and local-energy density properties have been calculated for a number of As4Sn (n = 3, 4 and 5) thioarsenide molecular crystals. On the basis of the distributions, the intramolecular As-S and As-As interactions classify as shared bonded interactions, and the intermolecular As-S, As-As and S-S interactions classify as closed-shell van der Waals (vdW) bonded interactions. The bulk of the intermolecular As-S bond paths link regions of locally concentrated electron density (Lewis-base regions) with aligned regions of locally depleted electron density (Lewis-acid regions) on adjacent molecules. The paths are comparable with intermolecular paths reported for several other molecular crystals that link aligned Lewis base and acid regions in a key-lock fashion, interactions that classified as long-range Lewis acid-base-directed vdW interactions. As the bulk of the intermolecular As-S bond paths (~70%) link Lewis acid-base regions on adjacent molecules, it appears that molecules adopt an arrangement that maximizes the number of As-S Lewis acid-base intermolecular bonded interactions. The maximization of the number of Lewis acid-base interactions appears to be connected with the close-packed array adopted by molecules: distorted cubic close-packed arrays are adopted for alacránite, pararealgar, uzonite, realgar and β-AsS and the distorted hexagonal close-packed arrays adopted by α- and β-dimorphite. A growth mechanism is proposed for thioarsenide molecular crystals from aqueous species that maximizes the number of long-range Lewis acid-base vdW As-S bonded interactions with the resulting directed bond paths structuralizing the molecules as a molecular crystal.

Original languageEnglish (US)
Pages (from-to)267-291
Number of pages25
JournalPhysics and Chemistry of Minerals
Issue number4
StatePublished - Apr 2011


  • Alacránite
  • Dimorphite
  • Pararealgar
  • Realgar
  • Uzonite

ASJC Scopus subject areas

  • General Materials Science
  • Geochemistry and Petrology


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