Defects are ubiquitous in functional materials and play a critical role in materials as simple as the binary rocksalt oxides and as complex as high-temperature superconductors . The importance of vacancy chemistry to molecular framework perovskites is becoming increasingly clear in many important families, including the hybrid metal-halide semiconductors , cyanide Prussian Blue analogue battery cathodes and magnetic formate perovskites , as the number of studies making use of defect-engineering in these materials grows. Perhaps the most widespread strategy for introducing defects is aliovalent doping, where an ion is replaced by an ion with a different charge. Thus far, cationic dopants have been the most widely used and have been introduced onto both the A, e.g. NH 3 CH 2 CH 2 NH 2+ iodide perovskites, the additional A site charge is compensated primarily by vacancies on the B site, and can be represented in the Kröger-Vink defect notation by