In the reaction of Mn(CO)5Br with the chelating ligand ο-N.N-dimethylaminophenyl diphenyl phosphine (PN) the two enantiomers of fac-Mn(CO)3(PN)Br are formed. Mn(CO)3⁻ (PN)Br interacts with CO/AlCl3 to give the salt [Mn(CO)4(PN)]AlHal4, which can be transformed into [Mn(CO)4(PN)]PF6. The diastereoisomeric compounds Mn(CO)3(PN)COOC10CH19, resulting from the addition of the menthoxide anion to the cation [Mn(CO)4(PN)]+, could not be separated because of their instability. Mn(CO)5Br reacts with the Schiff base NN*, derived from pyridine carbaldehyde(2) and R-α-phenyl ethyl amine, with formation of two isomers of Mn(CO)3(NN*)Br with different configurations at the Mn atom. Both diastereoisomers differ in their 1H NMR spectra and can be obtained in optically active form.