Open-chain hemiketal is stabilized by coordination to a copper (II)

Abstract

The hemiketal complex [Cu{NH2C(Me)2C(Ph)(OMe)O}2] (1) was generated by the reaction of [Cu(NCMe)4](BF4) and 4 equivs of 2,2-dimethyl-3-phenyl-2H-azirine in the presence of NCNMe2 in wet MeOH and isolated in 92% yield. In 1, the in situ formed hemiketal NH2C(Me)2C(Ph)(OMe)OH in its deprotonated form is stabilized due to chelation to copper(II). In the X-ray structure of 14MeOH, the intermolecular hydrogen bonding was detected between O and N atoms of the organic ligand and the HO group of solvated MeOH as well as between two molecules of the solvated MeOH. Three types of hydrogen bonds in the obtained structure were studied by the DFT calculations (M06/6-31++G** level of theory, MDF10 pseudopotentials on the Cu atoms) and topological analysis of the electron density distribution within the formalism of Bader's theory (QTAIM method). Estimated strength of these non-covalent interactions is 3–9kcal/mol.