Layered perovskites with Ruddlesden–Popper-type structures are fundamentally important for low-dimensional properties, for example, photovoltaic hybrid iodides and superconducting copper oxides. Many such halides and oxides are known, but analogous nitrides are difficult to stabilize due to the high cation oxidation states required to balance the anion charges. The aim of this project is the synthesis and investigation of the high-pressure behavior of the first Ruddelsen-Popper nitrides Pr2ReN4, Nd2ReN4, NdReN2 and Ce2TaN4 as well as their behavior in nitridation reactions in laser-heated diamond anvil cells.