Hochdruckverhalten anorganischer Verbindungen & Synthese halogenierter Formamidine

Möller, Andreas; Dronskowski, Richard (Thesis advisor); Oppel, Iris Marga (Thesis advisor)

Aachen (2019)
Dissertation / PhD Thesis

Dissertation, RWTH Aachen University, 2019


The thesis "High pressure behaviour of inorganic compounds and synthesis of halogenated formamidines" is divided into two parts. The first part deals with the behaviour of inorganic compounds under high pressures as they occur in diamond anvil cells. More precisely, the high-pressure behaviour of mercury and lead cyanamide was investigated. Furthermore, attempts were made to synthesize and characterize solid carbonic acid by high pressures. The two heavy metal cyanamides show the typical anisotropic compression behaviour of layered structures under pressure. For the lead compound, a transition to a more complex behaviour could be determined with increasing compression, in which a sevenfold coordination of the Pb2+ ion was avoided by tilting of the cyanamide unit. The attempt to determine basic crystallographic quantities of the crystal structure of carbonic acid by synthesis at high pressures was accompanied by the construction and development of several apparatuses: a ruby fluorescence spectrometer, a low temperature unit for glove boxes and the improvement of a high-pressure cell for neutron diffraction. These made it possible to index a previously unknown monoclinic phase of CO2 and D2O at 1.82(4) GPa. With a density of ρ = 2.4(1) g/cm3 it is plausible that this is the desired carbonic acid. In part 2 of this thesis, the crystal structures of the already known halogenated formamidinium halides XC(NH2)2X (X = Cl, Br, I) were determined for the first time. The existence of halogen bonds in the structures of Br and I could be proven. In addition, the first synthesis of halogenated formamidinium metalates from hydrogen cyanamide and the corresponding noble metal acids was successful. All compounds of part 2 are composed of halogenated formamidinium cations with two equally long partial C-N double bonds and isolated halides or halide metallates.