Synthesis and crystal structures of (C<sub>4</sub>H<sub>12</sub>N<sub>2</sub>)[Mn(HSeO<sub>3</sub>)<sub>2</sub&gt

Single crystals of two new complex hydroselenites with organic cations, (C4H12N2)[Mn(HSeO3)2Cl2] (1) and [(C4N12N2)Br]2[Mn(HSeO3)2Br2] (2), were obtained as the products of the reaction of piperazine, selenious acid and manganese halide in an aqueous medium. The crystal structures of 1 and 2 were determined by single-crystal X-ray diffraction analysis and are characterized by monoclinic symmetry (1: P21/c, a = 9.7557(7), b = 7.3930(5), c = 9.7660(6) Å, β = 116.839(7)°; 2: P21/c, a = 14.4093(3), b = 7.3822(1), c = 10.3051(3) Å, β = 101.553(2)°). The crystal structures of both compounds are constructed by alternating layers of the composition [Mn(HSeO3)2X2]2– (X = Cl, Br) and layers formed by piperazinium cations. Compound 1 is a structural analogue of the previously described compound (C4H12N2)[Cd(HSeO3)2Cl2], while the crystal structure of compound 2 belongs to a new structural type and contains layers including both piperazinium cations and bromine anions. The crystal structure of 2 is characterized by a modular structure.