Photochemistry of the [Fe(CN)(5)NO](2-)-thiolate system

The studied system consists of [Fe(CN)(5)NO](2-) 1, mercaptosuccinate or an other thiolate (RS-) and [Fe(CN)(5)N(O)SR](3-) 2 in equilibrium. The photoc hemical study has shown that both complexes 1 and 2 undergo either photooxi dation or photoreduction, depending on the excited state energy. The presen t study is focused on the low energy effects, which consist of an inner-sph ere photooxidation mode followed by a substitution pathway yielding pentacy anoferrate(III) complexes and NO or NOSR-. radicals for 1 and 2, respective ly. In the presence of mercaptosuccinate the [Fe-III(CN)(5)SR](3-) complex 3 and nitrosomercaptosuccinate were identified as the most stable products. The photochemical reactivity of the [Fe(CN)(5)N(O)SR](3-) complex thus res embles the photooxidation-substitution mode characteristic of [Fe(CN)(5)NO] (2-) but produces nitrosothiol instead of NO and needs considerably lower e nergy to be induced (MLCT band at lambda(max) 526 nm). Consequently, the ph otoreactivity of 2 creates the possibility of using the 1-RS- system to pho togenerate a nitrosothiol in situ using non-hazardous radiation.