Selenolato-Bridged Manganese(I)-Based Dinuclear Metallacycles as Potential Anticancer Agents and Photo-CORMs

Selenolato-bridged manganese­(I)-based dinuclear metallacycles [{(CO)3Mn­(μ-SeC6H5)2Mn­(CO)3}­(μ-L)] (1–4) were achieved in a single-step process by the self-assembly of dimanganese decacarbonyl, diphenyl diselenide, and flexible ditopic ester-functionalized pyridyl ligands [1, L = o-phenylene diisonicotinate (pdi); 2, L = 1,6-hexanediyl di-4-pyridine carboxylate (hdp); 3, L = 4-pyridine carboxylic acid diethylene glycol diester (pcadgd); 4, L = 4-pyridine carboxylic acid triethylene glycol diester (pcatgd)]. Synthesis of a series of selenolato-bridged dinuclear Mn­(I)-based metallacycles was facilitated via oxidative addition of C6H5Se–SeC6H5 to (CO)5Mn–Mn­(CO)5 with simultaneous coordination of flexible ditopic pyridyl linkers in an orthogonal fashion. The metallacycles were characterized by IR, UV–vis, NMR, and electrospray ionization-mass spectroscopic techniques and elemental analysis. Solid-state structural elucidation of 3 was carried out using single-crystal X-ray diffraction methods. In addition, anticancer activity studies were carried out for compounds 2–4 with various cancer cell lines. Furthermore, compound 3 was probed to evaluate its potential CO-releasing property using myoglobin assay.