Production of polyselenodipenicillamines, unique selenium compounds.

Selenite (H(2)SeO(3)) reacts with thiol compounds (RSH) under acidic conditions to form selenotrisulfides (RSSeSR, i.e. monoselenodithiols). The stoichiometry of the reaction is proposed as 4RSH+H(2)SeO(3)-->RSSeSR+RSSR+3H(2)O. Surprisingly, we found novel polynuclear selenium-containing compounds, i.e. polyselenodipenicillamines (PenSSe(2-4)SPen), in the reaction of D-penicillamine (PenSH) with H(2)SeO(3). The selenium-centered features of PenSSe(2-4)SPen were determined by (1)H-NMR and LC-MS/MS analyses, showing that the selenium isotope abundance patterns of the compounds were in good agreement with the theoretically-calculated ones. In order to better understand the mechanisms for PenSSe(2-4)SPen production, various molar ratio of H(2)SeO(3) (1/8 to 4 times of PenSH) was reacted with PenSH, and the concentration of the products was calculated from integral values of dimethyl proton signals for PenSSe(1-2)SPen as compared with methyl proton signals for acetic acid (an internal standard). Total PenSSe(1-2)SPen concentration was increased with increasing of H(2)SeO(3), in which concomitant decrease of PenSSPen (disulfide form of PenSH) was observed. Based on these results, we proposed the PenSSe(2-4)SPen production mechanisms being involved in penicillamine selenopersulfides (PenSSe(1-2)H).