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.