Copper(II) Activation of Nitrite: Nitrosation of Nucleophiles and Generation of NO by Thiols

Nitrite
(NO2–) and nitroso compounds
(E-NO, E = RS, RO, and R2N) in mammalian plasma and cells
serve important roles in nitric oxide (NO) dependent as well as NO
independent signaling. Employing an electron deficient β-diketiminato
copper­(II) nitrito complex [Cl2NNF6]­Cu­(κ2-O2N)·THF, thiols mediate reduction of nitrite
to NO. In contrast to NO generation upon reaction of thiols at iron
nitrite species, at copper this conversion proceeds through nucleophilic
attack of thiol RSH on the bound nitrite in [CuII]­(κ2-O2N) that leads to S-nitrosation
to give the S-nitrosothiol RSNO and copper­(II) hydroxide
[CuII]-OH. This nitrosation pathway is general and results
in the nitrosation of the amine Ph2NH and alcohol tBuOH to give Ph2NNO and tBuONO, respectively.
NO formation from thiols occurs from the reaction of RSNO and a copper­(II)
thiolate [CuII]-SR intermediate formed upon reaction of
an additional equiv thiol with [CuII]-OH.