Crystal structure of bis(μ2-4-tert-butyl-2-formylphenolato)-1:2κ3O1,O2:O1;3:4κ3O1,O2:O1-bis(4-tert-butyl-2-formylphenolato)-2κ2O1,O2;4κ2O1,O2-di-μ3-methoxido-1:2:3κ3O;1:3:4κ3O-di-μ2-methoxido-1:4κ2O;2:3κ2O-tetracopper(II)

The structure of the title compound, [Cu4(CH3O)4(C11H13O2)4], consists of dimeric dinuclear copper(II) complexes oriented around a centre of inversion. Within each dinuclear fragment, the two CuII atoms are in a distorted square-planar coordination sphere. Two neighbouring fragments are linked by four apical Cu—O contacts, yielding an overall square-pyramidal coordination environment for each of the four CuII atoms. The molecules are arranged in layers parallel to (101). Non-classical C—H...O hydrogen-bonding interactions are observed between the layers

Does Perthionitrite (SSNO^–) Account for Sustained Bioactivity of NO? A (Bio)chemical Characterization

Hydrogen sulfide (H₂S) and nitric oxide (NO) are important signaling molecules that regulate several physiological functions. Understanding the chemistry behind their interplay is important for explaining these functions. The reaction of H₂S with <i>S</i>-nitrosothiols to form the smallest <i>S</i>-nitrosothiol, thionitrous acid (HSNO), is one example of physiologically relevant cross-talk between H₂S and nitrogen species. Perthionitrite (SSNO^–) has recently been considered as an important biological source of NO that is far more stable and longer living than HSNO. In order to experimentally address this issue here, we prepared SSNO^– by two different approaches, which lead to two distinct species: SSNO^– and dithionitric acid [HON­(S)­S/HSN­(O)­S]. (H)­S₂NO species and their reactivity were studied by ¹⁵N NMR, IR, electron paramagnetic resonance and high-resolution electrospray ionization time-of-flight mass spectrometry, as well as by X-ray structure analysis and cyclic voltammetry. The obtained results pointed toward the inherent instability of SSNO^– in water solutions. SSNO^– decomposed readily in the presence of light, water, or acid, with concomitant formation of elemental sulfur and HNO. Furthermore, SSNO⁻ reacted with H₂S to generate HSNO. Computational studies on (H)­SSNO provided additional explanations for its instability. Thus, on the basis of our data, it seems to be less probable that SSNO^– can serve as a signaling molecule and biological source of NO. SSNO^– salts could, however, be used as fast generators of HNO in water solutions