Synthesis and characterization of cobalt cyclidene complexes with long polymethylene bridtges and their binding to small molecules

The synthesis of four novel cobalt(II) cyclidene complexes with long polymethylene bridges is described. These complexes have been found to reversibly bind dioxygen in a manner similar to that of their shorter bridged analogs. Dioxygen affinities are reduced for bridge lengths exceeding that of octamethylene, an effects on small-molecule binding that are associated with the long bridge have been examined by comparison of the X-ray crystal structure of th undecamethylene-bridged cobalt(III) complex with the shorter bridged analogues.