Abstract
The crystal structures of hydro-thermally synthesized silver(I) aluminium bis-[hydrogen arsenate(V)], AgAl(HAsO4)2, silver(I) gallium bis-[hydrogen arsenate(V)], AgGa(HAsO4)2, silver gallium diarsenate(V), AgGaAs2O7, and sodium gallium diarsenate(V), NaGaAs2O7, were determined from single-crystal X-ray diffraction data collected at room temperature. The first two compounds are representatives of the MCV-3 structure type known for KSc(HAsO4)2, which is characterized by a three-dimensional anionic framework of corner-sharing alternating M3+O6 octa-hedra (M = Al, Ga) and singly protonated AsO4 tetra-hedra. Inter-secting channels parallel to [101] and [110] host the Ag+ cations, which are positionally disordered in the Ga compound, but not in the Al compound. The hydrogen bonds are relatively strong, with O⋯O donor-acceptor distances of 2.6262 (17) and 2.6240 (19) Å for the Al and Ga compounds, respectively. The two diarsenate compounds are representatives of the NaAlAs2O7 structure type, characterized by an anionic framework topology built of M3+O6 octa-hedra (M = Al, Ga) sharing corners with diarsenate groups, and M+ cations (M = Ag) hosted in the voids of the framework. Both structures are characterized by a staggered conformation of the As2O7 groups.
Highlights
The crystal structures of hydrothermally synthesized silver(I) aluminium bis[hydrogen arsenate(V)], AgAl(HAsO4)2, silver(I) gallium bis[hydrogen arsenate(V)], AgGa(HAsO4)2, silver gallium diarsenate(V), AgGaAs2O7, and sodium gallium diarsenate(V), NaGaAs2O7, were determined from singlecrystal X-ray diffraction data collected at room temperature
The two diarsenate compounds are representatives of the NaAlAs2O7 structure type, characterized by an anionic framework topology built of M3+O6 octahedra (M = Al, Ga) sharing corners with diarsenate groups, and M+ cations (M = Ag) hosted in the voids of the framework
In the case of AgGa(HAsO4)2, the Ag+ cation occupies a split position (Fig. 1b), where Ag1 sits on the inversion centre, with a freely refined occupancy of 0.75 (2)
Summary
Metal arsenates often form tetrahedral–octahedral framework structures with potentially interesting properties, such as ion conductivity, ion exchange and catalytic properties (Masquelier et al, 1990, 1994a,b, 1995, 1996; Medvedev et al, 2003; Ouerfelli et al, 2007a, 2008; Pintard-Screpel et al, 1983; Rousse et al, 2013). A detailed study of the system M+–M3+– As–O–(H) was conducted, and a wide variety of new compounds and structure types were found and have been published (Schwendtner, 2006; Schwendtner & Kolitsch, 2004a,b, 2005, 2007a,b,c,d). Three different structure types for M1+M3+(HAsO4) compounds have been reported. The KSc(HAsO4) type (Schwendtner & Kolitsch, 2004a) has so far been the only known example; the two new protonated arsenates presented here are two further representatives of this structure type. The NaAlAs2O7 type (Driss & Jouini, 1994) is known for AgFeAs2O7 and NaFeAs2O7 (Ouerfelli et al, 2004), and the M12+M22+ representative CaCuAs2O7 (Chen & Wang, 1996). The two diarsenates presented here adopt the NaAlAs2O7 structure type
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: Acta crystallographica. Section E, Crystallographic communications
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
