[C6H17N3]4[Sb4V16O42]⋅2H2O and [NH4]4[Sb8V14O42]⋅2H2O— the first isolated Sb derivates of the [V18O42] family

The solvothermal syntheses and the crystal structures of the two new compounds [C6H17N3]4[Sb4V16O42]⋅2H2O (1) and [NH4]4[Sb8V14O42]⋅2H2O (2) are presented. Compound (1) crystallises in the triclinic space group P1¯ and (2) in the monoclinic space group P21/n. The structures can be derived from the [V18O42] archetype by replacing two VO5 square pyramids by two Sb2O5 units in (1) and four VO5 square pyramids by four Sb2O5 moieties in (2). In compound (1) the clusters are stacked along the b-axis in an AAA mode with the cations and water molecules occupying the interstitial space. Between the anions and cations strong N&sbnd;H⋯O hydrogen bonds are observed. Neighboured clusters exhibit a relatively short Sb&sbnd;O separation of 2.852 Å indicating a weak inter-cluster interaction. If this Sb&sbnd;O contact is considered the clusters are connected via Sb2V2O4 rings into infinite chains running along the a-axis. In compound (2) the anions are stacked along the b-axis in an …ABAB… fashion. Within the (100) plane every anion is surrounded by 6 neighboured clusters. Again, relatively short Sb&sbnd;O contacts (2.831–2.976 Å) are found which join the isolated clusters into layers extending in the (10−1) plane. The cations and water molecules are located between these layers. Several short N&sbnd;O and O&sbnd;O distances indicate strong hydrogen bonding between cations and anions respectively between the water molecules and the anions.