A molecule based on polyoxometalate acid and crown ether: synthesis and characterization of [(H 3O)(C 20H 24O 6)] 2[HPMo 12O 40]·C 20H 24O 6·3MeCN·H 2O (C 20H 24O 6=dibenzo-18-crown-6)

Abstract

The new molecule based on 12-molybdophosphate acid and dibenzo-18-crown-6, [(H 3O)(C 20H 24O 6)] 2[HPMo 12O 40]·C 20H 24O 6·3MeCN·H 2O 1, was synthesized in acetonitrile and characterized by elemental analyses, IR, 1H NMR, electrospray mass spectra and single crystal X-ray diffraction, indicating that it contains [(H 3O)(dibenzo-18-crown-6)] + cations, where oxonium ions are out of the planes defined by crown ether oxygen atoms, and disordered PMo 12O 40 3− anions with α-Keggin structure where the crystal has high lattice energy so that it is difficult to dissolve it. The crystallographic disorder averages Mo–Mo distances and Mo–O b/ c –Mo angles between the M 3 triplets and within the M 3 triplet. The interactions between crown ether molecules and oxonium ions are hydrogen-bonding with the O(crown ether)–OH 3 + distances of 2.510(10)–2.783(7) Å. The interactions between [(H 3O)(dibenzo-18-crown-6)] + cations and PMo 12O 40 3− anions are dominantly electrostatic. The electrical conductivity is <10 −7 S.cm −1.