1H NMR and X-ray studies on hydrogen bonding in alkyloxy ethanols and their MgCl2 adducts

Adducts of alkyloxy ethanols (2-isobutoxy ethanol, 2-isopropoxy ethanol, 2-ethoxy ethanol, and 2-methoxy ethanol) with MgCl2 were prepared in the presence of excess alkyloxy ethanol in molar ratios 5:1–15:1. MgCl2/2-isopropoxy ethanol and MgCl2/2-isobutoxy ethanol adducts were successfully crystallized and their structures determined by single-crystal X-ray diffraction. Alkyloxy ethanol molecules bind to magnesium in 2:1 mol ratio through oxygens of the alcohol and ether groups forming a chelated structure. In the binuclear complexes [(ipe)2MgCl2Mg(ipe)2][Cl]2 and [(ibe)2MgCl2Mg(ibe)2][Cl]2 (structures 1 and 2), where ipe stands for 2-isopropoxy ethanol and ibe for 2-isobutoxy ethanol, the two magnesium centers are connected by two chlorine bridges. The mononuclear structure cis-[Mg(ibe)2(H2O)2][Cl]2 (structure 3) contains, besides two alkyloxy molecules, two water molecules bound to magnesium. Hydrogen bonding in the adducts, in liquid and solid states, was studied by 1H NMR spectroscopy and X-ray diffraction, respectively. In liquid state, the sample concentration and temperature used in the measurements were observed to influence hydrogen bonding. All crystal structures show extensive hydrogen bonding from anionic chlorines to the OH hydrogen of alcohols or the water hydrogens.