Blue-light induced CO releasing properties of thiourea based manganese(I) carbonyl complexes

A new class of blue-light triggered carbon monoxide releasing molecules based on Mn(CO)₃Br(N,S) ((N,S) = N,S-bidentate thiourea ligands) has been reported in this work. The ¹H and ¹³C NMR analysis indicated that the thioureas coordinate to Mn(I) in the thione form. The stability test and the ability to derive CO to DMSO and myoglobin solution upon the exposure to 468 nm light source have been investigated. The benzothiazole-thiourea-CORM released only one CO equivalent, while the pyridine-analogs offered two molecules at the same experimental conditions. Natural bond orbital analysis has been carried out to give details about the hybridization of Mn–C and C[tbnd]O bonds, natural charge, electronic arrangement of metal ion and strength of interaction between Mn(I) and the coordination sites. Both functional, B3LYP and CAM-B3LYP compare well with the experimental findings, where the longest wavelength band is assigned to MLCT.