PHYSICOCHEMICAL STUDIES OF LITHIUM ION SOLVATION AND MACROCYCLIC COMPLEXATION IN ALUMINUM - TRICHLORIDE-BUTYLPYRIDINIUM CHLORIDE MOLTEN SALTS (MULTINUCLEAR NMR).

摘要

Multinuclear NMR measurements have been used to study the solvation of various metal ions in the AlCl(,3)-N-butylpyridinium chloride molten salt system. Potentiometry, far-IR spectrophotometry, and x-ray crystallography have provided important supplemental information regarding the nature of the various species and their interactions which occur in this ionic liquid. In addition, the complexation of the lithium ion by crown ethers and cryptand complexants in basic AlCl(,3)-BPCl melts has been investigated.; Lithium-7 NMR studies indicate that in basic melt at 40(DEGREES)C, the lithium ion exists as both the monomer (LiCl(,2)('-)) and the dimer (Li(,2)Cl(,4)('2-)) chlorocomplexes. Potentiometric data confirm that two chloride ions are associated with each lithium ion in basic melt solutions. Lithium-7 chemical shift and spin-lattice relaxation measurements, and the potentiometry results indicate that anions (other than the chloride ion) which are added to basic melt do not interact with the lithium ion.; Concentration formation constants for the 12C4, 15C5, B15C5, and 18C6 crown complexes of the lithium ion in basic melt have been determined from the variations of the ('7)Li chemical shifts with the crown/Li('+) mole ratios. The crown complex stabilities decrease in the order 15C5 (TURNEQ) > 12C4 > 18C6.; Slow chemical exchange has been observed in ('7)Li NMR studies of the complexation of the lithium ion with cryptands C211, C221, C222, and C2(,B)22 at 40(DEGREES)C and a field strength of 42.28 kG. Concentration formation constants for the C221, C222, and C2(,B)22 complexes have been determined, with the complex stabilities decreasing in the order C221 > C222 > C2(,B)22. The C2(,B)22(.)LiAlCl(,4) complex has been isolated from basic melt, and its crystal structure determined.; Potentiometric titrations of LiCl in basic melt with 15C5 and C2(,B)22 indicate that complexation proceeds with retention of the chloride ions in the crown complex, while the chloride ions are released into the solution in the process of cryptate formation.; Far-IR and multinuclear NMR methods have been used to confirm the existence of chlorocomplexes of various heavy metal ions in dilute basic melt solutions of the parent heavy metal chlorides. These complexes appear to be discrete, rather than polymeric species in these solutions.