Tetra-kis(di-propyl-ammonium) tetra-kis(oxa-lato-κ(2) O (1),O (2))stannate(IV) mono-hydrate: a complex with an eight-coordinate Sn(IV) atom.

In the title salt, [(CH3CH2CH2)2NH2]4[Sn(C2O4)4]·H2O, the Sn(IV) atom of the stannate anion is located on a special position with -42m symmetry. It is eight-coordinated by four chelating oxalate anions. The di-propyl-ammonium cation possesses mirror symmetry while the lattice water mol-ecule is disordered about a position with -42m symmetry and has an occupancy of 0.25. In the crystal, the anions and cations are linked by N-H⋯O hydrogen bonds, forming a three-dimensional network. This network is futher stabilized by weak O-H⋯O hydrogen bonds involving the water mol-ecules and oxalate O atoms. The crystal studied was refined as an inversion twin.

Dibenzyl-aza-nium (oxalato-κ(2)O,O')triphenyl-stannate(IV).

The title compound, (C(14)H(16)N)[Sn(C(6)H(5))(3)(C(2)O(2))], was synthesised by allowing C(2)O(4)(Bz(2)NH(2))(2) (Bz = benzyl) to react with SnPh(3)Cl. The asymmetric unit is built up by four SnPh(3)C(2)O(4) anions and four Bz(2)NH(2) cations which are related by a pseudo-inversion centre. Each Sn(IV) cation is five-coordinated by the three phenyl groups and two O atoms belonging to the chelating oxalate ligand; the coordination geometry is that of a distorted trigonal bipyramid. Anions and cations are linked through N-H⋯O hydrogen bonds into a layer structure parallel to (001). Moreover, the anion-cation pairs are associated by two bifurcated N-H⋯O hydrogen bonds, generating pseudo-dimers. One of the phenyl groups of one anion is disordered over two sets of sites in a 0.69:0.31 ratio. The Flack parameter value of 0.44 (1) indicates racemic twinning.

Bis(dicyclo-hexyl-ammonium) µ-oxalato-κO,O:O,O-bis-[aqua-(oxalato-κO,O)diphenyl-stannate(IV)].

The structure of the title compound, (C(12)H(24)N)(2)[Sn(2)(C(6)H(5))(4)(C(2)O(4))(3)(H(2)O)(2)], consists of a bischelating oxalate ion, located on an inversion center, which is linked to two SnPh(2) groups. The coordination sphere of the Sn(IV) ion is completed by a monochelating oxalate anion and a water mol-ecule. The Sn(IV) atoms are thus seven-coordinated. The discrete binuclear units are further connected by hydrogen bonds, leading to a supra-molecular crystal structure. The asymmetric unit contains one half dianion and one (Cy(2)NH(2))(+) cation.

Crystal structure of di-methyl-ammonium hydrogen oxalate hemi(oxalic acid).

Single crystals of the title salt, Me2NH2 (+)·HC2O4 (-)·0.5H2C2O4, were isolated as a side product from the reaction involving Me2NH, H2C2O4 and Sn(n-Bu)3Cl in a 1:2 ratio in methanol or by the reaction of the (Me2NH2)2C2O4 salt and Sn(CH3)3Cl in a 2:1 ratio in ethanol. The asymmetric unit comprises a di-methyl-ammonium cation (Me2NH2 (+)), an hydrogenoxalate anion (HC2O4 (-)), and half a mol-ecule of oxalic acid (H2C2O4) situated about an inversion center. From a supra-molecular point of view, the three components inter-act together via hydrogen bonding. The Me2NH2 (+) cations and the HC2O4 (-) anions are in close proximity through bifurcated N-H⋯(O,O) hydrogen bonds, while the HC2O4 (-) anions are organized into infinite chains via O-H⋯O hydrogen bonds, propagating along the a-axis direction. In addition, the oxalic acid (H2C2O4) mol-ecules play the role of connectors between these chains. Both the carbonyl and hydroxyl groups of each diacid are involved in four inter-molecular inter-actions with two Me2NH2 (+) and two HC2O4 (-) ions of four distinct polymeric chains, via two N-H⋯O and two O-H⋯O hydrogen bonds, respectively. The resulting mol-ecular assembly can be viewed as a two-dimensional bilayer-like arrangement lying parallel to (010), and reinforced by a C-H⋯O hydrogen bond.