Metal Iodides in Polyiodide Networks: Synthesis and Structure of Binary Metal Iodide−Iodine Compounds Stable under Ambient Conditions

The reaction between HgI2(C6N4H12) and HI in ethanol solution results in the binary metal iodide−iodine complexes
[C6N4H13]2(Hg2I6)1/2(HgI3)·1/2I2, which are stable under ambient conditions. The structure consists of C6N4H13+
cations, discrete trigonal HgI3- ions, and ···Hg2I62-···I2···Hg2I62-··· chains in the crystallographic b direction,
which are formed by I2 molecules connecting the bridging iodines of the Hg2I62- dimers. The intra- and
intermolecular I−I distances of iodine in the chain are 2.7402(15) and 3.438(1) Å, respectively. The Raman
spectrum of [C6N4H13]2(Hg2I6)1/2(HgI3)·1/2I2 confirms the interaction between the iodine molecules and Hg2I62-
ions. The structure of [NH4](HgI3)·H2O, obtained during the synthesis of [C6N4H13]2(Hg2I6)1/2(HgI3)·1/2I2, is also
reported. Crystal data for [C6N4H13]2(Hg2I6)1/2(HgI3)·1/2I2:  a = 14.275(3) Å, b = 19.721(4) Å, c = 10.416(2) Å,
orthorhombic space group Pbam; Z = 4. Crystal data for [NH4](HgI3)·H2O:  a = 8.7246(4) Å, b = 9.7860(3) Å,
c = 11.1103(4) Å, orthorhombic space group Ama2; Z = 4.