Crystal structure of (NH₄)₂[Fe^II₅(HPO₃)₆], a new open-framework phosphite

Abstract

(NH4)2[FeII 2(HPO3)6] exhibits an open-framework structure with channels in which disordered ammonium cations are situated.

Ax(H3O)2−xMn5(HPO3)6 (A = Li, Na, K and NH4): open-framework manganese(ii) phosphites templated by mixed cationic species

“…The third step in the thermal decomposition of 1-Li is observed above 500ºC. After the complete release of hydronium cations, a weight gain is exclusively observed and ascribed to the complete oxidation of 30 the phosphite groups and the formation of the inorganic residues. The main difference between the thermogravimetric curve of the as-synthesized compound and the sample exposed one month to ambient conditions is observed between 30 and 135ºC and related to the loss of adsorbed water molecules.…”

“…For 4-NH 4 , the loss of ammonium and hydronium cations seems to be less overlapped with the phosphite groups oxidation than in the other samples, and hence a higher weight loss value is observed in the first stage of the thermal analysis. Regarding 2-Na, the first weight loss (30)(31)(32)(33)(34)(35)(36)(37)(38)(39)(40)(41)(42)(43)(44)(45) 135ºC) is ascribed to adsorbed water molecules. Such behaviour was previously described for the lithium sample exposed to ambient conditions.…”

“…Meanwhile both parameters in 1-Li, stop growing in the 120-225 ºC temperature range, possibly due to small reorientation movements of the structural units before hydronium cations release. 30 …”

“…The systematic 25 2θ shift; peak shape (pseudo-Voigt); U, V, and W half-width parameters for the profile function; the previously obtained unit cell parameters; asymmetry parameters; and the background were refined. Starting from the space group and unit cell parameters of the lithium compound studied by single crystal X-ray diffraction, 30 we reached to good fits for all the compounds synthesized as powder samples with the following unit cell parameters: 1-Li, a=10.4618(5) Å, c= 9.4057(8) Å, V= 891.5(1) Å 3 ; 2-Na, a=10.4881(7) Å, c= 9.3984(10) Å, V= 895.3(1) Å 3 ; 3-K, a=10.4380(7) Å, c= 9.4076(10) Å, V= 887.7(1) Å 3 ; 4-NH 4 , 35 a=10.4699(9) Å, c= 9.4350(12) Å, V= 895.7(2) Å 3 ( Fig. 1(a) and Table S2).…”

“…1 HPO 3 groups can prevent self-interpenetration owing to a fewer number of P-O binding sites, opening the possibilities to construct new porous architectures with large channels that may 30 not be feasible in the classical phosphates family.…”