Guanidinium tetra-bromidomercurate(II).

The Hg atoms in the crystal structure of the title compound, (CH(6)N(3))(2)[HgBr(4)], are tetra-hedrally coordinated by four Br atoms and the resulting [HgBr(4)](2-) tetra-hedral ions are linked to the [C(NH(2))(3)](+) ions by bromine-hydrogen bonds, forming a three-dimensional network. In the structure, the anions are located on special positions. The two different Hg⋯Br distances of 2.664 (1) and 2.559 (1) Šobserved in the tetra-bromidomercurate unit are due to the connection of Br atoms to different number of H atoms.

Bis(guanidinium) tetra-iodidomercurate(II).

The Hg atom in the crystal structure of the title compound, (CH(6)N(3))(2)[HgI(4)], is tetra-hedrally coordinated by four I atoms. The [HgI(4)](2-) ions are inter-connected to the [C(NH(2))(3)](+) ions by N-H⋯I hydrogen bonds, forming a three-dimensional network. The four different observed Hg-I distances [2.760 (2), 2.7762 (15), 2.8098 (14) and 2.833 (2) Å] are consistent with four different (127)I NQR frequencies observed, showing the existence of four unique I atoms in the tetra-iodidomercurate unit.