Reactivity of Zinc Thiolate Bonds: Oxidative Organopolysulfide Formation and S₃ Insertion

Abstract

Zinc thiolate bonds are intriguing targets of study because of their redox noninnocence and prevalence in bioinorganic sites. A five-coordinate zinc dithiolate complex [Et4N]2[LZn] (H4L = N,N′-di­(2-sulfhydrylphenyl)-pyridine-2,6-dicarboxamide) was synthesized to study the oxidative reactivity of zinc thiolate bonds. Multiple chemically reversible reactions of the zinc thiolate bonds were identified. Oxidation of [Et4N]2[LZn] with iodine resulted in structural rearrangement to a bimetallic disulfide-bridged complex. In contrast, the addition of elemental sulfur to [Et4N]2[LZn] resulted in the insertion of a neutral S3 fragment into the Zn–thiolate bond to selectively form an unusual monometallic tetrasulfanido complex. When oxidized, this tetrasulfanido compound rearranged to form a bimetallic trisulfide-bridged complex. The observed diversity of zinc thiolate reactivity, particularly with sulfur, is likely important in biological contexts.

Hydrosulfide Oxidation at a Molybdenum Tetrasulfido Complex

“…For example, the reaction of H 2 S with a tristetraprolin (TTP) zinc finger protein resulted in persulfidation and complete oxidation of TTP in the presence of O 2 . Similarly, Ballesteros and Tsui recently demonstrated that Zn–S bonds can react with elemental sulfur to form organopolysulfides . Furthermore, sulfur extrusion has been observed from the reduction of zinc organotetrasulfides with triphenylphosphine (PPh 3 ), which highlights the potential for S-atom transfer from metal polysulfide motifs.…”

“…15 Similarly, Ballesteros and Tsui recently demonstrated that Zn−S bonds can react with elemental sulfur to form organopolysulfides. 16 Furthermore, sulfur extrusion has been observed from the reduction of zinc organotetrasulfides with triphenylphosphine (PPh 3 ), which highlights the potential for S-atom transfer from metal polysulfide motifs.…”

Synthesis of Terminal Bis(hydrosulfido) and Disulfido Complexes of Ni(II) from a Geometrically Frustrated Tetrahedral Ni(II) Chloride Complex

“…The reactivity of a β-diketiminate Ni I complex with elemental sulfur was investigated by Yao and Driess, which revealed the one-electron oxidation of the Ni I and formation of the first example of a Ni II supersulfido complex with a side-on S 2 – ligand . Sulfane sulfur insertion into Zn–S bonds can also be achieved with elemental sulfur as demonstrated by Ballesteros and Tsui and highlighted the role that redox inert metals may play in RSS regulation …”

“…10 Sulfane sulfur insertion into Zn−S bonds can also be achieved with elemental sulfur as demonstrated by Ballesteros and Tsui and highlighted the role that redox inert metals may play in RSS regulation. 11 In this report we investigate the reactivity of phenyltris( 12 has been employed in the stabilization of highvalent metal-nitrido, 13 oxo, 14,15 and peroxo species, 16 as well as in studying the unusual seesaw geometries adapted by Ni II . 17 This coordination environment provides new opportunities to investigate how RSS interact with metals in such environments where simple ligand substitution reactions are generally expected, but due to geometric frustration, new reaction pathways are discovered.…”

Synthesis and reactivity of a tris(carbene) zinc chloride complex

“…of a PPh 3 reductant. 12 The coordination chemistry of anions such as thionitrite (SNO − ) and perthionitrite (SSNO − ), which are subject to rapid reactivity in the presence of redox-active reagents, have also taken advantage of the redox-inert properties of zinc to form the first structurally characterized transition metal complexes of SNO − and SSNO − . 13…”