FTIR and multinuclear magnetic resonance studies of tris(oxaalkyl) boratesand their complexes with Li+ and Na+ cations

FTIR and NMR of H-1, C-13, B-11, Li-7 and Na-23 nuclei were used for the st udy of the complexation of Li+ and Na+ cations by three tris(oxaalkyl) bora tes. The NMR techniques proved the formation of complexes and the fluctuati on of Li+ and Na+ cations in the respective channels formed by three oxaalk yl chains. In the FTIR spectra of Li+ complexes with three tris(oxaalkyl) b orates, continuous absorption in the far-infrared region indicates the fast fluctuations of Li+ ion between O atoms of the channels. The dependence of the continua shape on the length of the channels, i.e., the number of mini ma in the multiminima potentials, demonstrates that the fluctuation of Liion occurs along the channel. Owing to the larger mass and diameter of the Na+ cation in the Na+-tris(oxaalkyl) borate complexes, only systems with lo nger channels show a large Na+ polarizability due to the fast fluctuation o f Na+ cations in a multiminima potential.