[NaCl][Cu(HSeO3)2], NaCl-intercalated Cu(HSeO3)2: synthesis, crystal structure and comparison with related compounds

Abstract

Abstract Single crystals of [NaCl][Cu(HSeO3)2] have been prepared by the chemical vapor transport reactions. Its crystal structure (monoclinic, C2/c, a = 13.9874(7), b = 7.2594(4), c = 9.0421(5) Å, β = 127.046(2)°, V = 732.81(7) Å3) is based upon electroneutral [Cu(HSeO3)2] sheets formed by corner sharing between the [CuO4] squares and (HSeO3) groups that are parallel to the (100) plane. Each (SeO2OH)– group forms the Oh1...O2 hydrogen bond to an adjacent hydroselenite group to constitute a [(SeO2OH)2]2– dimer that provides additional stabilization of the copper diselenite sheet. The [Cu(HSeO3)2] sheets alternate with the sheets consisting of zigzag–Na–Cl–Na–Cl–chains formed by Cl atoms and disordered Na sites. The chains are parallel to the c axis. The linkage between the alternating electroneutral [Cu(HSeO3)2] and [NaCl] sheets is provided by the Cu–Cl and Na–O bonds. The coordination of Na is fivefold and consists of three O and two Cl atoms. [NaCl][Cu(HSeO3)2] is a new member of the group of compounds based upon the M(HSeO3)2 layers (M2+ = Cu, Co, Cd). The prototype structure for this group is [Cu(HSeO3)2] that does not have any chemical species separating the copper hydroselenite layers. In other compounds, the interlayer space between the [Cu(HSeO3)2]0 layers is occupied by structural units of different complexity. [NaCl][Cu(HSeO3)2] can be considered as [Cu(HSeO3)2] intercalated with the NaCl layers consisting of one-dimensional–Na–Cl–Na–Cl–chains.