Synthesis, Structure, and Properties of Compounds in the NaHSO₄−CsHSO₄System. 1. Crystal Structures of Cs₂Na(HSO₄)₃and CsNa₂(HSO₄)₃

Abstract

Exploratory synthesis in the NaHSO4−CsHSO4 system, aimed at discovering novel proton conducting solids, resulted in the new compounds CsNa2(HSO4)3 and Cs2Na(HSO4)3. Single-crystal X-ray diffraction (performed at room temperature) revealed CsNa2(HSO4)3 to crystallize in the cubic space group P213 with lattice parameters a = 10.568(2) Å and Z = 4, whereas Cs2Na(HSO4)3, studied by both single-crystal neutron and X-ray methods, crystallizes in the hexagonal space group P63/m. The latter compound has lattice parameters a = 8.5712(17) and c = 9.980(2) Å, and Z = 2. The unit cell volumes are 1180.4(4) and 634.9(2) Å3, respectively, giving calculated densities of 2.645 and 3.304 mg m-3. Refinement using all observed reflections yielded a weighted residual, R w(F 2), of 0.0515 based on F 2 X-ray values for CsNa2(HSO4)3. For Cs2Na(HSO4)3 the analogous X-ray and neutron values were 0.0483 and 0.1715, respectively. Both structures contain a single, crystallographically distinct, asymmetric hydrogen bond (as confirmed by NMR investigations) and unique, three-membered (HSO4)3 rings. The geometric match between the NaO6 octahedra and the rings suggests the sodium polyhedra may serve to template the (HSO4)3 unit. In CsNa2(HSO4)3 the rings form a distorted cubic close-packed array. The Cs atoms are located within the “octahedral” sites of this array, and the Na atoms, within the “tetrahedral” sites. The rings in Cs2Na(HSO4)3 are linked together by NaO6 octahedra to form infinite Na(HSO4)3 chains that extend along [001]. The hexagonal compound exhibits disorder about the sulfate tetrahedron that suggests a P63/m → P6 phase transition may occur upon cooling.

Synthesis of an Organotin Oligomer Containing a Heptanuclear Tin Phosphonate Cluster by Debenzylation Reactions: X-ray Crystal Structure of {Na6(CH3OH)2(H2O)}- {[(BzSn)3(PhPO3)5(μ3-O)(CH3O)]2Bz2Sn}·CH3OH

“…Each of the Na2 and Na3 atoms is bonded to four oxygen atoms from three different phenylphosphonate ions. The Na−O(phosphonate) distances range from 2.205(7) to 2.757(10) Å, comparable to those observed in the related sodium compounds . In addition, the Na2 atom is further bonded to two methanol molecules, and the Na3 atom is further coordinated by one water molecule.…”

Intermediate temperature stable proton conductors based upon SnP2O7, including additional H3PO4

“…[7][8][9] For the latter case, significant amounts of time have been devoted to the investigation and modifications of oxo acid salts such as CsHSO 4 or CsH 2 PO 4 . [10][11][12][13][14][15][16][17] Although the acid salts could exhibit a high conductivity ($10 À2 S/cm) above 150 C, thermal decomposition of SO 4 2À ions in a reducing atmosphere may limit the application of sulfate based solid acid salts as electrolytes in fuel cells. 18 CsH 2 PO 4 has been shown to be a good electrolyte material for intermediate temperature fuel cells.…”

Влияние катионного замещения в Cs-=SUB=-1-2x-=/SUB=-Ba-=SUB=-x-=/SUB=-H-=SUB=-2-=/SUB=-PO-=SUB=-4-=/SUB=- на структурные свойства и протонную проводимость

“…Как известно, изо-морфизм структур возможен при одинаковых коорди-национных числах атомов [21], и степень совершен-ства структуры определяется близостью межатомных расстояний, состоянием химической связи и строением электронной оболочки атомов. При значительном отли-чии радиусов замещающих катионов (более 10−15%) и разнице электроотрицательностей, превышающей 0.4, возможность растворения ограничена, и структура сме-шанных кристаллов кислых солей, как правило, суще-ственно отличается от структур исходных солей [22]. • C и проходит в две стадии, суммарная потеря веса составляет 10.8%.…”