Synthesis and spectroscopic characterization of new organotin(IV) complexes with bis(3,5-dimethylpyrazol-1-yl)dithioacetate

New organotin(IV) derivatives containing the anionic ligand bis(3,5-dimethylpyrazolyl)dithioacetate [L₂CS₂]^? have been synthesized by reaction of SnR _n X_{4? n} (R?=?Me, Ph, ⁿ Bu or Cy; n?=?1–3) acceptors and Li[L₂CS₂]. Mononuclear complexes of the type [L₂CS₂]R _n SnCl_{4? n ?1}} have been obtained and fully characterized by elemental analyses and FT-IR in the solid state, and by NMR (¹H and ¹¹⁹Sn) spectroscopy, conductivity measurements and electrospray ionization mass spectrometry (ESI-MS) in solution. ESI-MS spectra of methanol solutions of diorganotin derivatives, recorded with fragmentor potentials of 0, 50, 100 and 150?V, show the occurrence at 150?V of peaks attributable to the loss of the CS₂ group from the ligands and the formation of stable tetraorganodistannoxane species.