Related Experiment Video
Updated: Apr 18, 2026

Chemiluminescence-based Assays for Detection of Nitric Oxide and its Derivatives from Autoxidation and Nitrosated Compounds
Published on: February 16, 2022
Copper nitrite reduction by thiols: mechanistic insights into NO release en route to copper thiolate formation
Naorem Jemes Meitei1, Yu-Ting Chu2, Chien-Hung Li1
1Department of Medicinal and Applied Chemistry, Drug Development and Value Creation Research Centre, Kaohsiung Medical University, Kaohsiung 807378, Taiwan. sodiohsu@kmu.edu.tw.
Abstract:
Nitrite reduction is a critical process in biological systems, with implications for disease pathology and therapeutic development. This study investigates the copper-mediated reduction of nitrite to nitric oxide (NO) using unsymmetrical β-diketiminato copper(II) nitrito complexes with thiol derivatives as reducing agents. The reaction of LCu(NO2) with 4-tert-butyl benzyl thiol (tBuBzSH), benzyl thiol (BzSH), and biologically active thiols like L-cysteine (Cys) yields quantitative NO, free ligand, disulfide, and an insoluble copper(I)-thiolate polymer (YPR), characterized by FT-IR, NMR, and X-ray photoelectron spectroscopy (XPS). Mechanistic analysis reveals a transient Cu(II)-thiolate intermediate (λmax = 590 nm) formed via acid-base exchange, generating nitrous acid (HNO2) that reacts with excess thiol to form S-nitrosothiol (RSNO). NO releases through RSNO, forming the stable Cu(I)-thiolate polymer. XPS confirms the presence of Cu(I) in YPtBuBz and YPBz as well as mixed-valent Cu(I/II) in YPCys with a clear satellite peak, which is supported by Auger parameter calculations. This work highlights the potential of copper complexes for NO generation and provides a deeper understanding of the underlying mechanisms.
Related Concept Videos
Preparation and Reactions of Thiols
Sulfur Assimilation
Nitriles to Amines: LiAlH4 Reduction
As shown below, the mechanism involves three steps. Firstly, the hydride ion acting as a nucleophile attacks the nitrile carbon to form an anion. In the second step, a second equivalent of the hydride ion attacks the anion to...
Preparation of Amines: Reduction of Oximes and Nitro Compounds
Though catalytic hydrogenation can reduce nitrobenzenes, the reduction is nonselective in the presence of other functional groups. For instance, if nitrobenzene contains an aldehyde group,...
Rate-Determining Steps
In a multistep reaction mechanism, one of the elementary steps progresses significantly slower than the others. This slowest step is called the rate-limiting step (or rate-determining step). A reaction cannot proceed faster than its slowest step, and hence, the rate-determining step limits the overall reaction rate.
The concept of rate-determining step can be understood from the analogy of a 4-lane freeway with a short-stretch of traffic-bottleneck caused due to...
Formation of Complex Ions

