Abstract
NO and H(2) S serve as signaling molecules in biology with intertwined reactivity. HSNO and HSSNO with their conjugate bases (-) SNO and (-) SSNO form in the reaction of H(2) S with NO as well as S-nitrosothiols (RSNO) and nitrite (NO(2)(-) ) that serve as NO reservoirs. While HSNO and HSSNO are elusive, their conjugate bases form isolable zinc complexes (Ph,Me) TpZn(SNO) and (Ph,Me) TpZn(SSNO) supported by tris(pyrazolyl)borate ligands. Reaction of Na(15-C-5)SSNO with (Ph,Me) TpZn(ClO(4) ) provides (Ph,Me) TpZn(SSNO) that undergoes S-atom removal by PEt(3) to give (Ph,Me) TpZn(SNO) and S=PEt(3) . Unexpectedly stable at room temperature, these Zn-SNO and Zn-SSNO complexes release NO upon heating. (Ph,Me) TpZn(SNO) and (Ph,Me) TpZn(SSNO) quickly react with acidic thiols such as C(6) F(5) SH to form N(2) O and NO, respectively. Increasing the thiol basicity in p-substituted aromatic thiols (4-X) ArSH in the reaction with (Ph,Me) TpZn(SNO) turns on competing S-nitrosation to form (Ph,Me) TpZn-SH and RSNO, the latter a known precursor for NO.