Amide-Functionalized Chalcogen-Bridged Flexible Tetranuclear Rhenacycles: Synthesis, Characterization, Solvent Effect on the Structure, and Guest Binding.

The synthesis of flexible rhenium(I)-based amide-functionalized chalcogen-bridged tetranuclear metallacycles of general formula [{(CO)Re(μ-ER)Re(CO)}(μ-L)] () was achieved by treating rhenium carbonyl with dialkyl/diaryl chalcogenide (RE-ER; E = S and Se) in the presence of ditopic flexible or semiflexible pyridyl ligand with amide functionality (L = ,'-bis(4-pyridylcarboxamide)-1,2-ethane (bpce) and ,'-bis(4-(4-pyridylcarboxamide)phenyl)methane (bpcpm)). Compounds were formed by multicomponent self-assembly under one-pot reaction conditions via oxidative addition of dialkyl/diaryl chalcogenide to rhenium carbonyl with pyridyl ligands. The resultant metallacyclophanes were characterized using elemental analyses, infrared, ultraviolet-visible, and NMR spectroscopic techniques.