M2L2-type metallacycles [M(CO)3Br(µ-pcadgd)]2 (1, M = Mn; 2, M = Re) were prepared by the reaction of equimolar amounts of M(CO)5Br and 4-pyridinecarboxylic acid diethyleneglycol diester (L = pcadgd). On the other hand, polyether spacer containing bromido-bridged M2(µ-Br)2L-type metallacycles [M2(CO)6(μ-Br)2(μ-pcadgd)] (3, M = Mn; 4, M = Re) were obtained by treating two equivalents of M(CO)5Br with one equivalent of 4-pyridinecarboxylic acid diethyleneglycol diester (pcadgd). Compounds 1–4 were characterized using elemental analyses, NMR, IR and UV–Vis absorption spectroscopic techniques. Formation of 1–4 was ascertained by ESI-mass spectrometry, while the structural elucidation of bromido-bridged compound 3 was carried out by single-crystal X-ray diffraction analysis. This research work comprises the first Mn(I)-based polyether spacer containing dinuclear metallacycles with/without a bromido-bridge, along with their Re counterparts. The metallacycles 1–4 were obtained in a single-step directly from M(CO)5Br via a two precursor self-assembly. © 2017 Elsevier B.V.