Spectroscopic and DFT studies of photoactivatable Mn(I) tricarbonyl complexes

• Published in: Applied organometallic chemistry 2019-07, Vol.33 (7), p.n/a
• Main Authors: Mansour, Ahmed M., Ragab, Mona S.
• Format: Article
• Language: English
• Subjects: Bonding strength; Carbon monoxide; Chemistry; Density functional theory; Energy absorption; Ligands; Light emitting diodes; Manganese ions; Mathematical analysis; Morpholine; Myoglobins; natural bond orbital analysis; PhotoCORMs; TD‐DFT; Time dependence
• ISSN: 0268-2605; 1099-0739
• DOI: 10.1002/aoc.4944

A combined experimental study and density functional theory calculations of fac‐[MnBr (CO)3L] complexes (L = 2‐(2′‐pyridyl)benzimidazole ligand, furnished with either morpholine (Lmorph) or phthalimido (Lphth) side‐chain) were performed using different spectral and analytical tools. The synthesized complexes released carbon monoxide upon the exposure to LED source light at 468 nm. Illumination of fac‐[MnBr (CO)3L] (10 μM) in the myoglobin solution (Mb) produced about 25 μM MbCO. The plateau of the CO release process is attained within 25 min. With the aid of time‐dependent density functional theory calculations, the observed lowest energy absorption transition at ~ 400 nm has a ground‐state composed of d (Mn)/π (pyridyl) and excited‐state of ligand π*‐orbitals forming MLCT/π‐π*. Natural population analyses of fac‐[MnBr (CO)3L] were carried out to get information about the strength of Mn–CO bonds, electronic arrangment and natural charge of manganese ion. Blue‐light triggered properties of dark‐stable pyridylbenzimidazole based manganese(I) tricarbonyl complexes were reported. DFT calculations ruled out the role of the appendage of the ligand system on the CO release process.