Cs₂Co^II(C₂O₄)₂·4H₂O

Abstract

Dicaesium cobalt(II) dioxalate tetrahydrate [tetraaquabis("oxalato)cobalt(II)dicaesium(I)], Cs 2 Co II (C 2 O 4) 2 Á4H 2 O, has a layered structure and is isotypic with Cs 2 Mg(C 2 O 4) 2 Á4H 2 O. The unique Co atom shows octahedral coordination, with a mean CoÐO bond length of 2.084 A Ê. The Cs atom is irregularly coordinated by nine O atoms. Layers of CoO 4 (H 2 O) 2 octahedra, whose non-water O ligands belong to nearly planar bidentate oxalate groups, are separated by corrugated layers of Cs atoms. Medium-strong hydrogen bonds provide connections within the layer planes. All atoms are in general positions except the Co atom, which lies on a twofold axis. Comment As part of recent work on the crystal chemistry and topology of double metal oxalates (Kolitsch, 2004; Fleck & Kolitsch, 2004), the title compound has been prepared by crystallization from an aqueous solution at room temperature, and its crystal structure has been determined from single-crystal X-ray intensity data collected at 293 K. Cs 2 Co II (C 2 O 4) 2 Á4H 2 O is isotypic with Cs 2 Mg(C 2 O 4) 2 Á4H 2 O, the new structure type that was recently described by Kolitsch (2004). The title compound crystallizes in space group C2/c and exhibits a layered atomic arrangement. The asymmetric unit contains one unique Cs atom, one Co, two C, six O atoms and four H atoms. Only the Co atom is located on a special

M+M3+2As(HAsO4)6and α- and β-M+M3+(HAsO4)2(M+M3+= RbAl or CsFe): six new compounds crystallizing in three closely related structure types

“…(Gagné & Hawthorne, 2015). The grand mean As-O bond distance in AsO 6 octahedra in inorganic compounds is 1.830 (2) Å according to Schwendtner & Kolitsch (2007a); this value was determined based on 33 AsO 6 octahedra of 31 compounds. Gagné & Hawthorne (2018) determined a value of 1.830 (28) Å based on only 13 AsO 6 octahedra in AsO 6 -containing compounds meeting all selection criteria as defined in Gagné & Hawthorne (2016).…”

“…Colourless RbAl 2 As-(HAsO 4 ) 6 was the sole reaction product. Light-blue CsFe 2 -As(HAsO 4 ) 6 was accompanied by crystals of CsAs 3 O 8 (Schwendtner & Kolitsch, 2007a). The crystals were extracted mechanically and were not further washed.…”

“…These structures can exhibit interesting properties, such as ion conductivity and ion exchange, as well as unusual catalytic, piezoelectric, nonlinear optical (frequency doubling) or magnetic features (Cambon et al, 2003(Cambon et al, , 2005Chouchene et al, 2017;d'Yvoire et al, 1983d'Yvoire et al, , 1986d'Yvoire et al, , 1988Kato, 1975;Krempl, 2005;Masquelier et al, 1990Masquelier et al, , 1994Masquelier et al, , 1995Masquelier et al, , 1996Masquelier et al, , 1998Ouerfelli et al, 2007Ouerfelli et al, , 2008Pintard-Scré pel et al, 1983;Ren et al, 2015;Sun et al, 2017;Vitins et al, 2000). To further increase the knowledge about the possible compounds and structure types of arsenates, a comprehensive study of the system M + -M 3+ -O-(H)-As 5+ (M + = Li, Na, K, Rb, Cs, Ag, Tl, NH 4 ; M 3+ = Al, Ga, In, Sc, Fe, Cr, Tl) was undertaken, which led to a large number of new compounds, most of which have been published (Baran et al, 2006;Kolitsch & Schwendtner, 2004;Schwendtner, 2006, Schwendtner & Kolitsch, 2004a,b, 2005, 2007a,b,c,d, 2017a,b,c,d, 2018.…”

“…Two of the six new compounds contain the rather rare AsO 6 group. Out of all reported arsenates(V) only about 3% contain AsO 6 polyhedra according to our review paper (Schwendtner & Kolitsch, 2007a), which provides an overview of all known compounds containing AsO 6 groups and their bond-length statistics. In addition to the 31 known compounds described in our review, the following few compounds have been described since then: -SrAs 2 O 6 and -SrAs 2 O 6 (Weil et al, 2009), PdAs 2 O 6 (Orosel & Jansen, 2006;Reehuis et al, 2012;Zhao et al, 2017) and Ba 2 As 4 O 12 (Weil, 2016).…”

M3+(H2AsO4)(H2As2O7) (M3+= Al, Ga) and In2(H2AsO4)2(H2As2O7)2: a new layer structure type and a new framework structure type containing the rare H2As2O72−group

“…Arsenates, similar to phosphates or silicates, tend to form compounds with strong mixed tetrahedral-octahedral (T-O) framework structures with a wide range of topologies, which can exhibit interesting properties, such as ion conductivity, ion exchange or unusual magnetic, piezoelectric, nonlinear optical (frequency doubling) or catalytic features (Cambon et al, 2003(Cambon et al, , 2005Chouchene et al, 2017;d'Yvoire et al, 1983d'Yvoire et al, , 1986d'Yvoire et al, , 1988Kato, 1975;Krempl, 2005;Masquelier et al, 1990Masquelier et al, , 1994Masquelier et al, , 1995Masquelier et al, , 1996Masquelier et al, , 1998Ouerfelli et al, 2007Ouerfelli et al, , 2008Ren et al, 2015;Sun et al, 2017;Vitins et al, 2000). To further expand the knowledge about the possible compounds and structure types of arsenates, a comprehensive study of the M + -M 3+ -O-(H)-As 5+ system (M + = Li, Na, K, Rb, Cs, Ag, Tl, NH 4 ; M 3+ = Al, Ga, In, Sc, Fe, Cr, Tl) was undertaken, which led to a large number of new compounds, several of which have been reported (Baran et al, 2006a;Schwendtner, 2006;Schwendtner & Kolitsch, 2004a,b, 2005, 2007a,b,c,d, 2017a, including the two M 3+ arsenates ScAsO 4 ÁH 2 O (Baran et al, 2006b;Kolitsch & Schwendtner, 2004) and InAsO 4 ÁH 2 O , which are both isotypic with MnMoO 4 ÁH 2 O (Clearfield et al, 1985).…”