Synthesis and characterization of novel, metal-rich room temperature ionic liquids and computational modeling of 23Na NMR shifts of organometallic compounds

Abstract

ABSTRACT A A series of room temperature ionic liquids (RTILs) containing MX42- (where M = Co, Ni and X = Cl, I) as the counterion have been synthesized from alkyl imidazolium chlorides and the appropriate MX2 species. A secondary series of RITLs in which the imidazolium cation has been replaced by trihexyl(tetradecyl)phosphonium chloride is also introduced. These salts are liquid at ambient temperatures (ca. 20 °C) and deep blue in color. The thermal behavior and decomposition products of these salts have been probed and provide new synthetic routes to nanoparticulate materials. Also presented is their entrapment in silica matrices to form ionogels and introductory probes into their electrochemical behavior. ABSTRACT B Computational modeling was carried out on a variety of 23Na organometallic compounds. Geometry optimization was carried out with DFT calculations in the Gaussian 03W suite of programs. The gauge-including atomic orbital (GIAO) method was then used to calculate their 23Na NMR magnetic shielding values. It was determined that the chemical shift of unsubstituted Na(C3H5) was very sensitive to the presence of coordinated THF (20 ppm upfield shift). The addition of silyl groups to the allyl has an even larger effect (30 ppm). This is in contrast with NaCp, where coordinated THF causes only a 4 ppm upfield shift.