Aggregation of Hydrogen Bonded Dimeric Tri-Organotin Amino Substituted Pyrimidine-2-Thiolates

The synthesis of six tri-organotin compounds with 4-amino and 4,6-diaminopyrimidine-2-thiolate is described. The compounds have the general formula R3Sn(thiolate) where R = Me, Bu, or Ph. The compounds are investigated by a variety of spectroscopic techniques both in solution and in the solid state. The environment around the tin centres proves to be tetrahedral with monodentate thiolate anions as is inferred from the infrared and NMR spectra. The coordination sphere is not affected even by the presence of DMSO as solvent. In the solid state, the crystal structure determination of the trimethyl and triphenyltin derivatives of the 4,6-diaminopyrimidine-2-thiolate ligand, reveal an association into centrosymmetric dimers through N–H⋯N hydrogen-bonding interactions leaving the organotin site practically unaffected. However, in addition to the classical hydrogen bonding, weaker N–H⋯RS and N–H⋯Rπ interactions are also present and play an important role in determining further aggregation of these dimers which gives rise to a three-dimensional polymeric structure in the case of the trimethyltin and a layer of dimers in the case of the triphenyltin derivative, respectively.