Preliminary measurements of [FeFe]-hydrogenase model complexes were made in a previous experiment using EMU (RB 1010177). The results were interpreted in combination with DFT calculations and indicated muonium addition to the Fe centre at a terminal position. Notably, they also indicated the possibility of muonium binding to a CO ligand. This application will continue to investigate [Fe2(µ-pdt)(CO)4(PMe3)2] in both solid and liquid phases using the HiFi instrument. The objectives are to fully characterise all addition sites by measuring the expected Δ1 resonances hinted to from the repolarisation curves of the previous experiment. Once identified in solid and liquid phases, we would like study these resonances as a function of temperature. We would also like to investigate the rate of addition by measuring ALC spectra over a number of concentrations.