Spectrochemistry of solutions. Part 21.—Inner- and outer-sphere complexes of lithium with thiocyanate in acetonitrile solutions

Abstract

Solutions of lithium thiocyanate in acetonitrile and in acetonitrile containing tetra-alkylammonium salts have been examined by infrared spectrophotometry. Analysis of the spectra obtained from acetonitrile solutions has yielded formation constants for the inner- and outer-sphere 1:1 complexes with log values of 3.87 and 3.05, respectively. When added perchlorate is present only the inner-sphere complex is formed with log K= 2.5, but when fluoroborate is present the logK value is 2.26. The effects of the added anion are attributed to its forming an outer-sphere complex, {[Li(MeCN)₄]X} and a triple ion {[Li(MeCN)₃NCS]X}^–.