Oxophilicity of Silicon(IV) in Silanethiols Facilitates the Generation of Thionitrite and Perthionitrite from a Binuclear Zinc(II)-bis(nitrito) Complex

Abstract

A detailed study of the reactivity of a Zn(II)-bis(nitrito) complex, [Zn2(BPMP)(ONO)(κ-NO2)]1+ (2), toward R3SiSH/R3SiS– and R3SiCl (R = Ph, iPr) in comparison to R1SH/R1S– (R1 = Ph3C, PhCH2) and PhCH2Br is presented. Unlike the negligible (for R1SH/R1S–) or less reactive (for PhCH2Br) nature of their carbon analogues, the stronger oxophilic nature of Si(IV) in R3SiSH/R3SiS– and R3SiCl allows facile reactions with the coordinated NO2– in 2 to generate the physiologically relevant S/N “crosstalk” species, SNO– and SSNO–, and R3SiONO, respectively, which in turn produces NO in high yields. Based on the characterization of all the products and the intermediates by a combination of X-ray structural and spectroscopic methods, mechanisms for all these new reactions have been proposed. Furthermore, a new synthetic method involving the reaction of R3SiSH and NO2– has been introduced, which allows the isolation of SSNO– as [Na(15-C-5)][SSNO], followed by the reaction of SSNO– with Ph3P to produce [Na(15-C-5)][SNO], both of which have been characterized by single-crystal X-ray structure determination and spectroscopic methods. The present work, thus, for the first time, utilizes the oxophilicity of Si(IV) reagents to generate S/N “crosstalk” species from a Zn(II)-bis(nitrito) complex.