Stoichiometric Control in H ₂ S-Mediated Nitrite Reduction at a Zn-site: Intercepting SNO ¹⁻ , SSNO ¹⁻ and HONO Intermediates
- 1Department of Chemistry
- 2Southern Methodist University
- 3Georgetown University
Abstract
Hydrogen sulfide (H 2 S) and nitrite participate in intertwined signaling chemistry, yet the factors governing product selectivity between nitric oxide (NO) and nitroxyl (HNO) and the underlying reaction pathways remain poorly defined. Here, we establish that reduction of a zinc-nitrite complex by H 2 S follows stoichiometry-dependent product selectivity. With 2 equiv of H 2 S, the reaction generates NO and HNO-derived nitrous oxide (N 2 O) trapped in 46.3% ± 2.1% and 19.7% ± 1.5%, yields, respectively. UV-vis and 15 N NMR spectroscopy along with phosphine-based intermediate trapping and DFT studies support a nucleophilic attack pathway involving zinc-bound thionitrite (SNO − ) and perthionitrite (SSNO − ) intermediates. We independently synthesize and crystallographically characterize the zinc-perthionitrite complex, identifying isomers with cis-ĸ 2 -S,O and unprecedented Y-shaped ĸ 2 -S,S coordination modes in the solid-state. In contrast, 5 equiv of H 2 S favors an acidbase pathway involving spectroscopically intercepted nitrous acid (HONO) intermediate and affords NO in 94.6% ± 1.5% yield, with only trace N 2 O. Reaction with hydrosulfide (HS − ) instead, generate a zinc-hydrosulfide-nitrite adduct without nitrite reduction; subsequent protonation produces NO exclusively. Together, these findings establish H 2 S stoichiometry and proton availability as complementary determinants of competing nitrite reduction pathways that control NO versus N 2 O selectivity at a redox-inactive zinc center.
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BibTeX
@misc{mishra2026stoichiometric,
title = {{Stoichiometric Control in H ₂ S-Mediated Nitrite Reduction at a Zn-site: Intercepting SNO ¹⁻ , SSNO ¹⁻ and HONO Intermediates}},
author = {Saikat Mishra and Anagha Kuruvayil and Esther Olatunji and Jeffery A. Bertke and Pokhraj Ghosh},
howpublished = {ChemRxiv},
year = {2026},
month = oct,
doi = {10.26434/chemrxiv.15010250/v1},
url = {https://chemrxiv.org/doi/full/10.26434/chemrxiv.15010250/v1},
note = {CC BY},
}
RIS
TY - UNPB
TI - Stoichiometric Control in H ₂ S-Mediated Nitrite Reduction at a Zn-site: Intercepting SNO ¹⁻ , SSNO ¹⁻ and HONO Intermediates
AU - Saikat Mishra
AU - Anagha Kuruvayil
AU - Esther Olatunji
AU - Jeffery A. Bertke
AU - Pokhraj Ghosh
PY - 2026
DA - 2026/10/12
PB - ChemRxiv
DO - 10.26434/chemrxiv.15010250/v1
UR - https://chemrxiv.org/doi/full/10.26434/chemrxiv.15010250/v1
AB - Hydrogen sulfide (H 2 S) and nitrite participate in intertwined signaling chemistry, yet the factors governing product selectivity between nitric oxide (NO) and nitroxyl (HNO) and the underlying reaction pathways remain poorly defined. Here, we establish that reduction of a zinc-nitrite complex by H 2 S follows stoichiometry-dependent product selectivity. With 2 equiv of H 2 S, the reaction generates NO and HNO-derived nitrous oxide (N 2 O) trapped in 46.3% ± 2.1% and 19.7% ± 1.5%, yields, respectively. UV-vis and 15 N NMR spectroscopy along with phosphine-based intermediate trapping and DFT studies support a nucleophilic attack pathway involving zinc-bound thionitrite (SNO − ) and perthionitrite (SSNO − ) intermediates. We independently synthesize and crystallographically characterize the zinc-perthionitrite complex, identifying isomers with cis-ĸ 2 -S,O and unprecedented Y-shaped ĸ 2 -S,S coordination modes in the solid-state. In contrast, 5 equiv of H 2 S favors an acidbase pathway involving spectroscopically intercepted nitrous acid (HONO) intermediate and affords NO in 94.6% ± 1.5% yield, with only trace N 2 O. Reaction with hydrosulfide (HS − ) instead, generate a zinc-hydrosulfide-nitrite adduct without nitrite reduction; subsequent protonation produces NO exclusively. Together, these findings establish H 2 S stoichiometry and proton availability as complementary determinants of competing nitrite reduction pathways that control NO versus N 2 O selectivity at a redox-inactive zinc center.
ER -