Unraveling the General Trend of the Reaction of Nitrite with Diiron(II)-polychalcogenides

Detailed structural and spectroscopic investigation of the reactivity of nitrite (NO₂⁻) with three binuclear Fe(II)-polychalcogenido complexes, [Fe₂(BPMP)(En)]¹⁺ (E = S, n = 5; E = Se, n = 4) and [Fe₂(BPMP)(S₆)(NCS)], in comparison with a Zn(II) analogue, [Zn₂(BPMP)(S₅)]¹⁺ (BPMP¹⁻ is the anion of 2,6-bis[[bis(2-pyridylmethyl)amino]methyl]-4-methylphenol), establishes, for the first time, a general trend for the product formation and the reaction mechanism. While all the reactions generated nitric oxide (NO) involving the generation of perthionitrite (SSNO⁻) or its selenium analogue, the reactions involving Fe(II) always produced the dinitrosyl iron complexes (DNICs), [Fe(E₅)(NO)₂]¹⁻ (E = S, Se), and binuclear Fe(II)-chalcogenido/-hydrochalcogenido complexes, which is in sharp contrast to the formation of binuclear Zn(II) complexes featuring the coordinated SnO²⁻ ligand (n = 3, 4). The present study shows that the reaction of diiron(II)-polychalcogenido complexes with NO₂⁻ follows a very different path than that followed by the Zn(II) analogues and is not affected by the presence of an additional redox-silent ligand, such as SCN⁻. Furthermore, the isolation of a unique diiron(II)-trihydrosulfido complex as an analytically pure complex in the reaction of a diiron(II)-pentasulfido complex and NO₂⁻ indicated the hitherto unknown prospects of the reactivity of NO₂⁻ with coordinated polychalcogenides for new chemical transformations.