Role of hydrogen-bonding in the formation of polar achiral and nonpolar chiral vanadium selenite frameworks.

A series of organically templated vanadium selenites have been prepared under mild hydrothermal conditions. Single crystals were grown from mixtures of VOSO(4), SeO(2), and either 1,4-dimethylpiperazine, 2,5-dimethylpiperazine, or 2-methylpiperazine in H(2)O. Each compound contains one-dimensional [VO(SeO(3))(HSeO(3))](n)(n-) secondary building units, which connect to form three-dimensional frameworks in the presence of 2,5-dimethylpiperazine or 2-methylpiperazine. Differences in composition and both intra-secondary building unit and organic-inorganic hydrogen-bonding between compounds dictate the dimensionality of the resulting inorganic structures. [1,4-dimethylpiperazineH(2)][VO(SeO(3))(HSeO(3))](2) contains one-dimensional [VO(SeO(3))(HSeO(3))](n)(n-) chains, while [2,5-dimethylpiperazineH(2)][VO(SeO(3))(HSeO(3))](2)·2H(2)O contains a three-dimensional [VO(SeO(3))(HSeO(3))](n)(n-) framework. The use of racemic 2-methylpiperazine also results in a compound containing a three-dimensional [VO(SeO(3))(HSeO(3))](n)(n-) framework, crystallizing in the noncentrosymmetric polar, achiral space group Pca2(1) (no. 29), while analogous reactions containing either (R)-2-methylpiperazine or (S)-2-methylpiperazine result in noncentrosymmetric, nonpolar chiral frameworks that crystallize in P2(1)2(1)2 (no. 18). The formation of these noncentrosymmetric framework materials is dictated by the structure, symmetry, and hydrogen-bonding properties of the [2-methylpiperazineH(2)](2+) cations.

Bis(adamantan-1-aminium) hydrogen phosphate fumaric acid sesquisolvate.

The asymmetric unit of the title compound, 2C(10)H(18)N(+)·HPO(4) (2-)·1.5C(4)H(4)O(4), contains two adamantan-1-aminium cations, one hydrogen phosphate anion, and one and a half mol-ecules of fumaric acid, one of which exhibits crystallographic inversion symmetry. Each HPO(4) (2-) anion is hydrogen bonded, via all of its O atoms, to four NH(3) (+) groups of the adamantan-1-aminium cations, forming chains along [100]. These chains are, in turn, inter-connected via a set of O-H⋯O hydrogen bonds involving the fumaric acid solvent mol-ecules, forming layers parallel to (001). Weak C-H⋯O inter-actions lead to a consolidation of the three-dimensional set-up.

Tris(5-amino-1H-1,2,4-triazol-4-ium) dihydrogenphosphate hydrogen-phosphate trihydrate.

In the crystal structure of the title molecular salt, 3C2H5N4(+)·HPO4(2-)·H2PO4(-)·3H2O, the phosphate-based framework is built upon layers parallel to (010) made up from the H2PO4(-) and HPO4(2-) anions and water mol-ecules, which are inter-connected through O-H⋯O hydrogen bonds. The organic cations are located between the phosphate-water layers and are connected to them via N-H⋯O hydrogen bonds. The bond-length features are consistent with an imino resonance form for the exocyclic amino group, as is commonly found for a C-N single bond involving sp(2)-hybridized C and N atoms.