Molecular complex morpholine-CO2-H2O

Morpholine absorbs CO2 and H2O in air to form a molecular complex: morpholinium-1-morpholinecarboxylate-H2O. The structure of the complex was characterized by X-ray single crystal diffraction, 1H NMR and FT-IR. The crystal structure was determined to be triclinic, space group P1¯ with a = 6.494(2) Å, b = 8.098(4) Å, c = 13.533(4) Å, α = 96.99(3)°, β = 102.57(2)°, γ = 104.15(3)°, Z = 2. The complex is stabilized via three hydrogen bonds between the three components, N…O electrostatic attraction and O…O interaction (electron transfer). Due to electron transfer of the carbamate ion, the oxygen atom in water molecule is strongly negatively charged and the OH bond is considerably shorter than that of free water molecules. The formation of the molecular complex is a reversible process and will decompose upon heating. The mechanism of formation and stabilization is further investigated herein.