Cascade chemistry in azacryptand cages: bridging carbonates and methylcarbonates

Abstract

The different tendencies of dinuclear azacryptates of the m-CH₂C₆H₄CH₂ and 2,5-furano-spaced hosts L¹ and L² to catalyse CO₂ uptake-reactions within these sterically-protected host cavities are examined. Bridging methylcarbonates are generated catalytically upon exposure of methanol solutions of L¹, but not L², di-transition cation cryptates to atmospheric CO₂. X-Ray crystallographic structures of homodinuclear μ-carbonato cryptates of both ligands and μ-methylcarbonato cryptates of L¹ with later first transition series cations are reported. ESI-MS spectra show loss of H₂CO₃ from μ-carbonato cryptates in collision activation experiments.