Ion Association. Comparison of Spectroscopic and Conductance Values of Association Constants

Article abstract of DOI:10.1021/j150666a049

Molar conductances of potassium, rubidium, and cesium picrate and of cesium tetraphenylborate have been determined in 2-butanone at 25 deg C over a concentration range of 0.1-1.6 mmol L^-1.These Λ,C data together with those for lithium and sodium already determined in this laboratory were fitted by using the Lee-Wheaton (LW), the Pitts (P), the Fuoss 78 (F), and the Justice (J) conductance equations to obtain values of ion association constants, K_A, and limiting molar conductances.Spectrophotometric absorbance changes were measured for sodium and cesium picrate and remeasured for lithium and tetra-n-butylammonium picrate at 380 nm and 25 deg C over a concentration range of 0.02-1.4 mmol L^-1.Values of the cesium-133 NMR chemical shifts of cesium picrate were determined over a concentration range of 0.1-3 mmol L^-1 while those for cesium tetraphenylborate were determined over a range from 0.25 to 10 mmol L^-1.We calculated values of ion assiciation constants for the various salts using this spectroscopic data.The values of K_A determined spectroscopically and the values determined conductimetrically are the same within experimental error with one exception; for cesium tetraphenylborate, the NMR value depends on the concentration range of data included in the analysis.