The new luminescent carbonyl compounds [Mn-(Oxa-H)(CO) 3 Br] (1) and [Mn(Oxa-NMe 2 )(CO) 3 Br] (2) were synthesized and fully characterized. Complexes 1 and 2 showed CO release under blue light (λ 453 ). Spectroscopic techniques and TD-DFT and SOC-TD-DFT calculations indicated that 1 and 2 release the Oxa-H and Oxa-NMe 2 coligands in addition to the carbonyl ligands, increasing the luminescence during photoinduction.

Currently, there is great interest in the study of water-soluble metal compounds capable of releasing carbon monoxide, due to their potential therapeutic use. This paper reports the synthesis, spectroscopic characteristics and CO release properties of three water-soluble manganese(I) carbonyl compounds [Mn(aaz)(CO) 3 ]Br (1; where aaz = 6-amino-6-methylperhydro-1,4-diazepine), [Mn(Me 2 aaz)(CO) 3 ]Br (2; where Me 2 aaz = 6-amino-1,4,6-trimethyl-1,4-diazacycloheptane) and [Mn(tacn)(CO) 3 ]Br (3; where tacn = 1,4,7-triazacyclononane), that can act as photoCORMs (where CORM is carbon monoxide-releasing molecule). The main aim was to propose a mechanism for the CO release. Compounds 1-3 are capable of releasing carbon monoxide when exposed to light (λ 385 and λ 410) and thus, act as photoCORMs. The formation of a biscarbonyl intermediate was identified during the photo-release process at λ 385 and the quantum yields and rates of CO release were determined. The proposed CO release mechanisms involve two steps, where photo and redox processes take place, and compounds 1 and 2 exhibit a slightly different mechanism from compound 3. A good understanding of the CO photo-release mechanism is very important with regard to the development of more efficient compounds, particularly those intended for medical applications.

The title neutral copper complex, [Cu2Cl4(C8H17N3O2)2], shows a binuclear center with a Cu—(μ-Cl)2—Cu core, in which each copper ion is coordinated by the N,N,O donor atoms of the tridentate ligand 1,4,6-trimethyl-6-nitro-1,4-diazepine (meaaz-NO2) and three chloride exogenous ligands. Each metal ion is facially coordinated by meaaz-NO2 through N,N,O donor atoms, whereas two bridging and one terminal chloride ions occupy the other face of the highly Jahn–Teller-distorted octa­hedron. Two N atoms from tertiary amine groups of the meaaz-NO2 ligand and two exogenous Cl atoms with short Cu—N and Cu—Cl distances define the equatorial plane. The coordination around each CuII ion is completed by another Cl atom and an O atom from the NO2 group, in the axial positions. The binuclear complex exhibits a centrosymmetric structure with point symmetry .