Synthesis, Characterization, and Reactivity of Alkyldisulfanido Zinc Complexes

The alkyldisulfanido zinc complexes TpiPr,iPrZn(SSR) and TpPh,MeZn(SSR) where TpiPr,iPr is hydridotris-((3,5-isopropyl)pyrazolyl)borate, TpPh,Me is hydridotris-((3-phenyl,5-methyl)pyrazolyl)borate, and (SSR) is tert-butyldisulfanido or triphenylmethanedisulfanido were synthesized by reaction between the corresponding hydroxo complexes TpZn(OH) and the synthetic persulfide RSSH. All the complexes were characterized by elemental analysis and 1H NMR spectroscopy, and representative members of the class were also structurally characterized. The reactivity of the alkyldisulfanido TpZn(SSR) complexes with thiols was studied. In the absence of base, a simple exchange reaction between the alkyldisulfanido ligand and the thiol was observed in dichloromethane; when in the presence of base, the corresponding hydrogen(sulfido) complexes TpZn(SH) were obtained. The mechanism of the latter reaction has been studied and does not involve the coordinated alkyldisulfanido group. Reaction of the hydrogen(sulfido) complexes TpiPr,iPrZn(SH) with the thiosulfonate PhCH2S-SO2CF3 did not yield the expected alkyldisulfanido complex but benzyltrisulfide and a new complex tentatively assigned as TpiPr,iPrZn(O2SCF3).