1,4-diazabicyclo[2.2.2]octane-1,4-diium dihydrogen phosphate monohydrate from X-ray and neutron data

Abstract

Dihydrogen phosphate / Proton conductivity / Single crystal structure analysis / Neutron diffraction Abstract. The three-dimensional skeleton of the structure of the title compound is formed by the chains of the hydrogen phosphate units running approximately parallel to the c-axis. The units are coupled to the chains by three types of hydrogen bonds: strong symmetric O--H--O (O . . . O ¼ 2.424(4) and 2.425(4) A) and the moderate P--O--H . . . O--P and P--O . . . (H 2 O) . . . O--P, respectively. Molecules of the doubly protonated 1,4-diazabicyclo[2.2.2]octane moieties are placed in the voids and in addition for electrostatic interactions they are also hydrogen bonded to the chains of PO 4 tetrahedra. The DC conductivity measured at the room temperature along the baxis is very low (% 7 Â 10 À11 S cm À1 ), while in the perpendicular plane it is for more than two or three orders higher and the nonlinear current vs. potential dependence was registered.

Ab initio structure determination of 3,4-diaminopyridin-1-ium dihydrogen phosphate

“…The phosphate group in 3,4-DAPP is a slightly deformed tetrahedra with a minimum spread of the O-P-O bond angles (Table III). As expected, the P-O bond distances fall into two groups, and the protonated P-O vertices show the expected lengthening of the P¼O bonds (Blessing, 1988;Mahmoudkhani and Langer, 2002;Demir et al, 2003;Smrčok et al, 2009;Balamurugan et al, 2010;Kaman et al, 2011;Marouani et al, 2011). The structure of the 3,4-DAPP consists of dihydrogen phosphate tetrahedra linked by moderately strong (Jeffrey, 1997) (Spek, 2003).…”

Anilinium dihydrogen phosphate

“…2). The building blocks of the inorganic layer are deformed H 2 PO 4 tetrahedra with two narrow groups of O-P-O angles (median values $105 and $111 ) and with the P-O bond lengths falling into two groups (Table 1); the P-O(H) bonds are, as expected, longer than the other presumably P O bonds (Blessing, 1986;Mahmoudkhani & Langer, 2002;Demir et al, 2003;Smrčok et al, 2009;Balamurugan et al, 2010;Kaman et al, 2011;Marouani et al, 2011). Examination of the geometry of the anilinium cations forming the organic layers shows that the values of the bond distances, bond angles and torsion angles have expected values (Elmokhtar et al, 1995).…”

Preparation of quaternary pyridinium salts as possible proton conductors

“…These anion chains in the direction of crystallographic axis c are not mutually connected by other hydrogen bonds and can thus be considered to be "one-dimensional". This structure contains therefore motifs that determine the ability of the substance to carry protons, like in the case of amino guanidinium(1+) dihydrogen phosphate (Němec et al, 2004), 1,4-diazabicyclo[2.2.2]octane-1,4-diium dihydrogen phosphate monohydrate (Smrčok et al, 2009;Kaman & Havlíček 2005), and other similar compounds (Taraba, 2012). Consequently, the anion network is connected by sufficiently short hydrogen bonds that pass through the structure in a single, given direction.…”

“…The proton exhibits proton conductivity in the direction of these chains. In the work of Smrčok et al (2009), a crystal of 1,4-diazabicyclo[2.2.2]octane-1,4-diium dihydrogen phosphate monohydrate was studied in which, while it forms a spatial network of various types of hydrogen bonds, the proton conductivity in the direction of channels formed of dihydrogen phosphate anions connected by hydrogen bonds with lengths of 2.424Å and 2.425Å can be observed. In another study (Kaman et al, 2011), the base (diazabicyclooctane) was quaternized on the nitrogen atoms, excluding thus the incorporation of cations in the hydrogen bond system.…”