Coordination chemistry of alkali and alkaline earth cations: Synthesis and X-ray crystal structure of cesium (picrate) (benzo-15-crown-5) Cs+C6H2N3O7-(C14H20O5)

K. Venkatasubramanian, K. Joshi, N. S. Poonia, W. R. Montfort, S. R. Ernst, M. L. Hackert

Research output: Contribution to journalArticle

15 Scopus citations

Abstract

Crystals of the Cs+ Pic- (B15C5) complex (Pic=picrate; B15C5=benzo-15-crown-5) (Mr=629.3) are yellow prisms which belong to the triclinic space group Pī with a=7.377(4), b=11.372(2), c=14.806(2) Å, α=90.31(1), β=91.06(2), γ=108.32(2)0, Z=2, Dx=1.77, and Dm=1.77 g cm-3. Final R=0.055 for 3575 observed reflections out of a total of 4004 measured reflections. Cesium forms a 1:1 anion paired complex with B15C5 like sodium rather than a charge separated sandwich structure as found for potassium and expected for cesium in view of the ion-cavity radius concept. The Cs cation is 9-coordinate involving the five crown oxygens (Cs...O, 3.00(1) to 3.24(1) Å), the phenoxide (Cs...O-, 3.03(1) Å) and an ortho nitro group oxygen (Cs...O, 3.01(1) Å) of the picrate counteranion and, uniquely, with two additional oxygens (Cs...O, 3.17(1) and 3.40(1) Å) from a para nitro group of the picrate belonging to the adjacent molecule in the lattice. The Cs+ ion lies 2.07 Å out of the mean plane formed by the crown oxygens. This system provides the first structural evidence that the interaction stoichiometry of an alkali cation with a cyclic multidentate ligand is not a function of the ion and cavity size alone but also of its Lewis acid strength as modified by the charge neutralizing anion.

Original languageEnglish (US)
Pages (from-to)453-459
Number of pages7
JournalJournal of Inclusion Phenomena
Volume3
Issue number4
DOIs
StatePublished - Dec 1985

Keywords

  • X-ray structural analysis
  • benzo-15-crown-5
  • cesium ion
  • picrate ion

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Chemistry(all)

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