title: Anion-Receptor Mediated Oxidation of Carbon Monoxide to Carbonate by Peroxide Dianion.
abstract: The reactivity of peroxide dianion O2(2-) has been scarcely explored in organic media due to the lack of soluble sources of this reduced oxygen species. We now report the finding that the encapsulated peroxide cryptate, [O2⊂mBDCA-5t-H6](2-) (1), reacts with carbon monoxide in organic solvents at 40 °C to cleanly form an encapsulated carbonate. Characterization of the resulting hexacarboxamide carbonate cryptate by single crystal X-ray diffraction reveals that carbonate dianion forms nine complementary hydrogen bonds with the hexacarboxamide cryptand, [CO3⊂mBDCA-5t-H6](2-) (2), a conclusion that is supported by spectroscopic data. Labeling studies and (17)O solid-state NMR data confirm that two-thirds of the oxygen atoms in the encapsulated carbonate derive from peroxide dianion, while the carbon is derived from CO. Further evidence for the formation of a carbonate cryptate was obtained by three methods of independent synthesis: treatment of (i) free cryptand with K2CO3; (ii) monodeprotonated cryptand with PPN[HCO3]; and (iii) free cryptand with TBA[OH] and atmospheric CO2. This work demonstrates CO oxidation mediated by a hydrogen-bonding anion receptor, constituting an alternative to transition-metal catalysis.
authors.affiliation: Department of Chemistry, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139-4307, United States.
authors.forename: Matthew
authors.initials: M
authors.lastname: Nava
authors.affiliation: Department of Chemistry, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139-4307, United States.
authors.forename: Nazario
authors.initials: N
authors.lastname: Lopez
authors.affiliation: Department of Chemistry, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139-4307, United States.
authors.forename: Peter
authors.initials: P
authors.lastname: Müller
authors.affiliation: Department of Chemistry, Queen's University , 90 Bader Lane, Kingston, Ontario K7L3N6, Canada.
authors.forename: Gang
authors.initials: G
authors.lastname: Wu
authors.affiliation: Department of Chemistry and Chemical Biology, Harvard University , 12 Oxford Street, Cambridge Massachusetts 02138, United States.
authors.forename: Daniel G
authors.initials: DG
authors.lastname: Nocera
authors.affiliation: Department of Chemistry, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139-4307, United States.
authors.forename: Christopher C
authors.initials: CC
authors.lastname: Cummins