Oxidative addition of diaryldichalcogen ligands (REER) to ruthenium carbonyl (Ru3(CO)12) followed by the addition of halogen (X2) afforded chalcogen-bridged Ru(II)-based metallacycles of general formula [X(CO)3Ru(μ-ER)2Ru(CO)3X] (1-10), where E = S, Se, and Te; R = phenyl, tolyl, and benzyl; and X = Br and I. Compounds 1-10 were characterized using IR, UV-vis, and NMR spectroscopic techniques. Molecular structures of the metallacycles have been elucidated by single-crystal X-ray diffraction methods that confirm the dimeric nature of metallacycles, wherein the two Ru(CO)3X moieties are held together by the bridging aryl chalcogenide ligands. © 2013 American Chemical Society.