Multiorganyltin Compounds. Designing a novel phosphate-selective carrier

A series of distannyl derivatives, 1–9, were studied for their application as phosphate‐selective carriers in polymer‐based liquid membranes. A drastically different potentiometric behavior was observed depending on the distance between the tin(IV) coordinating centers and the ligands attached to them. Some of the compounds examined, i.e. (PhSnBr2)2CH2(1) and (Me3SiCH2SnCl2CH2)2 (3) showed very high potentiometric selectivity towards phosphate over other lipophilic anions such as perchlorate and thiocyanate. Results indicate that (1) the optimal number of CH2 groups between the Sn‐centers are either one or three, (2) the electron‐withdrawing power of the organic ligands attached to Sn‐centers strongly influences the overall response towards phosphate, and (3) the steric effect of the organic substituents is important in the potentiometric selectivity observed.