Synthesis of Non-Innocent Thiazolidinyl-thiolate Zinc Complexes and Their Reactivity with Perthionitrite, Sulfur, and Nitrite

This document describes the syntheses, anion exchange, and characterization of metal (Zn and Fe) thiazolidinyl-thiolate complexes. Zn or Fe bis(methylthiazolidinyl)pyridine dichloride complexes were synthesized using one-pot condensation and metalation reactions. These complexes can be deprotonated to ring-open one of the methylthiazolidine rings to form a thiolate arm (LZnCl). Anion exchange of the monochloride complex with Me3OTf results in the self-assembly of a thiolate-bridged trimer [LZn]3[OTf]3. This trimer contains an anion binding pocket driven by hydrogen bonding interactions, binding a OTf– anion. The H-bond associated OTf– is easily substituted for either I– or NO3– ([(LZn)3I]2+ or [(LZn)3NO3]2+). If a more strongly coordinating anion is used, the trimer dissociates back to monomers, allowing for the synthesis of an array of congeners differentiated from LZnCl only by the bound anion (LZnX). The reactivity of [LZn]3[OTf]3 with perthionitrite, sulfur, and nitrite was then explored. The reaction of [LZn]3[OTf]3 with –SSNO dissociated the trimer and forms a sulfur inserted, disulfanide perthionitrite zinc complex (LSZnSSNO). This complex decomposes, over hours to release NO. When any of the LZnX ligands are reacted with S, multiple species are formed. Whether the species are from S8 insertion into the thiolate bond or from thiolate oxidation is still unknown. The nitrite bound congener (LZnONO) forms similar products when reacted with S8 as those seen with other LZnX complexes. Unlike the sulfur reacted products of other LZnX complexes, which are stable, the products of LZnONO with S8 decompose over time releasing NO, suggesting the nitrite is non-innocent in this reaction.