Speciation of organotin compounds in NaCl aqueous solution: interaction of mono-, di- and tri-organotin(IV) cations with nucleotides 5' monophosphates

Formation constants for complex species of mono-, di- and tri-alkyltin(IV) cations with some nucleotide 5′-monophosphates (AMP, UMP, IMP and GMP) are reported, at T = 25°C and at I = 0.16 mol l-1 (NaCl). The investigation was performed in the light of speciation of organometallic compounds in natural fluids in the presence of nucleotides whose biological importance is well recognized. The simple and mixed hydrolytic complex species formed in all the systems investigated in the pH range 3-9 are (L = nucleotide; M = organotin cation Rx Sn(4-x)+, with x = 1 to 3): ML+, ML(OH)0 and ML(OH)2 - for the system CH3Sn3+-L (L = AMP, IMP, UMP); ML0 and ML(OH)- for the system (C2H5) 2Sn2+-L (L = AMP, IMP, UMP); ML-, ML(OH) 2-, MLH0 and M2L(OH)- for the system (C2H5)3Sn+-L (L = AMP); ML, ML(OH)2- and M2L0 for the system (C 2H5)3Sn+-L (L = IMP, UMP). As expected, owing to the strong tendency of organotin(IV) cations to hydrolysis in aqueous solution, the main species formed in the pH range of interest of natural fluids are the mixed hydrolytic ones.