NO and H2S serve as signaling molecules in biology with intertwined reactivity. HSNO and HSSNO with their conjugate bases −SNO and −SSNO form in the reaction of H2S with NO as well as S‐nitrosothiols (RSNO) and nitrite (NO2−) that serve as NO reservoirs. While HSNO and HSSNO are elusive, their conjugate bases form isolable zinc complexes Ph,MeTpZn(SNO) and Ph,MeTpZn(SSNO) supported by tris(pyrazolyl)borate ligands. Reaction of Na(15‐C‐5)SSNO with Ph,MeTpZn(ClO4) provides Ph,MeTpZn(SSNO) that undergoes S‐atom removal by PEt3 to give Ph,MeTpZn(SNO) and S=PEt3. Unexpectedly stable at room temperature, these Zn‐SNO and Zn‐SSNO complexes release NO upon heating. Ph,MeTpZn(SNO) and Ph,MeTpZn(SSNO) quickly react with acidic thiols such as C6F5SH to form N2O and NO, respectively. Increasing the thiol basicity in p‐substituted aromatic thiols 4−XArSH in the reaction with Ph,MeTpZn(SNO) turns on competing S‐nitrosation to form Ph,MeTpZn‐SH and RSNO, the latter a known precursor for NO.

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Copper nitrite reductases (CuNIRs) convert NO 2 − to NO as well as NO to N 2 O under high NO flux at a mononuclear type 2 Cu center. While model complexes illustrate N−N coupling from NO that results in symmetric trans-hyponitrite [Cu II ]− ONNO−[Cu II ] complexes, we report NO assembly at a single Cu site in the presence of an external reductant Cp* 2 M (M = Co, Fe) to give the first copper cis-hyponitrites [Cp* 2 M]{[Cu II ](κ 2 -O 2 N 2 )[Cu I ]}. Importantly, the κ 1 −N-bound [Cu I ] fragment may be easily removed by the addition of mild Lewis bases such as CNAr or pyridine to form the spectroscopically similar anion {[Cu II ](κ 2 -O 2 N 2 )} − . The addition of electrophiles such as H + to these anionic copper(II) cis-hyponitrites leads to N 2 O generation with the formation of the dicopper(II)-bis-μ-hydroxide [Cu II ] 2 (μ-OH) 2 . One-electron oxidation of the {[Cu II ](κ 2 -O 2 N 2 )} − core turns on H-atom transfer reactivity, enabling the oxidation of 9,10dihydroanthracene to anthracene with concomitant formation of N 2 O and [Cu II ] 2 (μ-OH) 2 . These studies illustrate both the reductive coupling of NO at a single copper center and a way to harness the strong oxidizing power of nitric oxide via the neutral cishyponitrite [Cu](κ 2 -O 2 N 2 ).

VH and THW conceived the synthetic approach; VH carried out synthetic experiments; VH and PG performed electrochemical measurements; VH and JAB performed crystallographic analysis; IMD, CJT, and DN collected XAS data, KML, and SC collected EPR data, IMD and KML carried out electronic structure calculations and interpreted spectroscopic data, VH, KML, and THW wrote the manuscript with assistance by JHF.