B-podand complexes with sodium ions: the reaction heats and PM5 semiempirical calculation

The complexation reactions of two types of tris(oxaalkyl) borates (B-podands with CH3 or C16H33 terminal groups) with Na+ cations have been studied by calorimetric and PM5 theoretical methods. Both methods provide evidence for formation of the respective complexes with Na+ cations of different stoichiometry. For compounds with short oxaalkyl chains the formation of 1:1 complexes and for compounds with longer oxaalkyl chains the formation of 1:x (x > 1) complexes has been found. The stoichiometry of the complexes estimated from the HOF values of the complexes is in well agreement with the calorimetric results. The structures of the complexes are visualised using semiempirical PM5 method.