Complexes of the H5O2+ and H3O+ cations with polyethers in water saturated dichloroethane solutions. A combined IR spectroscopic and quantum mechanics study

摘要

We report combined IR spectroscopic and quantum mechanical studies on the interactions between hydrated protonn(H3Ou0001 and H5O2nu0001) and polyethers (L = 15-crown-5, 18-crown-6, benzo-18-crown-6 and polyethylene glycols PEG-400nand PEG-600) in 1,2-dichloroethane (DCE) solution saturated with water, in the presence of non-coordinatingnchlorinated cobalt dicarbollide anions. The state of the hydrated proton and composition of the complexes are shownnto depend on the nature and concentration of the ligand. Thus, 15-crown-5 forms [H3Ou0001u0002L] and [H5O2nu0001u00022L] com-nplexes at small and high concentrations of L, respectively. At all studied concentrations, 18-crown-6 and benzo-18-crown-6nform only [H3Ou0001u0002L] type complexes, whereas PEGs form 1 : 1 complexes with H5O2nu0001. The coordination patternsnof the hydrated proton depend on the topology, flexibility/rigidity and the number of donor centres of L. In then[H3Ou0001u0002(18c6)], [H3Ou0001u0002(B18c6)] and [H5O2nu0001u00022(15c5)] complexes, the hydrated proton forms preferentially O–H u0002u0002u0002 OLnlinear hydrogen bonds. In [H3Ou0001u000215c5], H3Ou0001 interacts with all 5 O-atoms of 15c5 via one linear and two asymmetricnbifurcated H-bonds. We also report the first IR characterization of the [H5O2nu0001u00024H2O] cation complex in an organicnsolution.