Lastly, we find a change in the bond angles within the Fe octahedra, which shows that the FeC 6 and FeN 6 octahedra are not only rotated, but also slightly deformed with respect to the cubic crystal environment. Ideally, these angles should all amount to 90°, but in the rhombohedral phase the octahedra are slightly distorted. While the FeC 6 octahedra are stretched in the direction of the c-axis, the FeN 6 octahedra are getting compressed, which leads to inverse trends in the change of bond angles of these octahedra. The C-Fe-C angles within one layer perpendicular to the c-axis are narrowed, while the angles between carbons in different layers are increased and exactly the other way around for the angles between iron and nitrogen. The change is more pronounced for the Fe carbons angles, but even there does not exceed 4°total. We propose that these changes are caused by the presence of intercalated sodium ions. Due to the proximity of the sodium atoms the negatively charged nitrogens bend towards them, stretching the FeN 6 octahedra in the a/b plane. This directly results in a compression of the octahedra in the c-direction, which is partly compensated by the stretching of the Fe-C 6 octahedra. This change in the ligand field around the Fe atoms is also the reason for the further splitting of the t 2g states into a 1g /e g states being energetically beneficial, as described in the Introduction. These structural changes are verified to actually occur in this material by the experimental data on NaMnHCF.