Formation of Mixed-Ligand Metal Salts in Organic Phase at Cation-Exchange Extraction with Tetraphenylboronic Acid Salts
A significant extraction of calcium and yttrium chlorides by solutions of the corresponding tetraphenylborates in tributyl phosphate was revealed due to the formation of mixed complex compounds in the organic phase. It was shown that lithium, calcium, and yttrium tetraphenylborates are largely dissociated in the organic phase into ions. The process was studied by conductometric method. Based on the data obtained, it was assumed that the cause of the formation of mixed halide complexes is the high energy of the solvated ion pairs [CaL<sub> n </sub>]<sup>2+</sup>(A<sup>-</sup>)<sub>2 </sub>and [YL<sub> m </sub>]<sup>3+</sup>(A<sup>-</sup>)<sub>3 </sub>in organic solutions, which significantly decreases during the exchange of large tetraphenylborate anions to small chloride anions, possibly with the formation of solvated ion pairs with a lower charge of the cationic part of the complex [CaL<sub> n -1</sub>Cl]<sup>+</sup>A<sup>-</sup> or [YL<sub> m -2</sub>Сl<sub>2</sub>]<sup>+</sup>A<sup>- </sup>.