Tricarbonylmanganese(I) complexes of the ligands tris(imidazol-4-yl)phosphane (4-tipH), tris(1,4-diisopropylimidazol-2-yl)phosphane (2-tipiPr2), tris(pyridin-2-yl)phosphane (tpp) and tris(N-methylimidazol-2-yl)carbinol (2-ticNMe) were prepared. These act as N,N,N tripodal chelators. The solid-state structure of Mn(CO)3(tpp)]OTf was determined by X-ray diffraction. The potential of these complexes to act as photoactivatable CO-releasing molecules (PhotoCORMs) was studied with the UV/Vis spectroscopy-based myoglobin assay as well as by time-resolved IR spectroscopy. Within the series of compounds prepared, the steric bulk of the imidazolyl groups seems to significantly influence the CO-release kinetics and stoichiometry when using the myoglobin assay. In contrast, the time-resolved IR data suggest release of all carbonyl ligands upon irradiation. This effect points to a much closer association of myoglobin and PhotoCORMs than previously thought and will require further investigation.