Equilibria involved in the diorganotin(IV) and triorganotin(IV) phosphomycin interaction in aqueous solution

The interaction of the dimethyltin(IV) and trimethyltin(IV) cations with the phosphomycin disodium salt, Na-2[(1R,2S)-1,2-epoxypropylphosphonate], has been investigated using potentiometric and UV-visible techniques at 25 degrees C and 0.1 M ionic strength (NaClO4) in aqueous solution. The species Me2SnLH+, Me2SnL, Me2SnL22-, Me2SnLOH- and Me2SnL(OH)(2)(2-) (L = phosphomycinate(2-)) for dimethyltin(IV)-phosphomycinate, and the species Me3SnL-, and Me3SnLOH2- for trimethyltin(IV)-phosphomycinate systems were considered. The protonation of the phosphomycinate(2-) and formation constants of the complexes formed in solution were calculated using different computer programs. The speciation diagrams of the various complex species were evaluated as a function of pH. The involvement of different ligand functional groups in the binding to organotin(IV) is discussed. Copyright (c) 2007 John Wiley & Sons, Ltd.