Chelate‐Thiolate‐Coordinate Ligands Modulating the Configuration and Electrochemical Property of Dinitrosyliron Complexes (DNICs)

As opposed to the reversible redox reaction ({Fe(NO)₂}¹⁰ reduced‐form DNIC (NO)₂Fe(S(CH₂)₃S)]^2? ( 1 )?{Fe(NO)₂}⁹ oxidized‐form (NO)₂Fe(S(CH₂)₃S)]^?), the chemical oxidation of the {Fe(NO)₂}¹⁰ DNIC (NO)₂Fe(S(CH₂)₂S)]^2? ( 2 ) generates the dinuclear {Fe(NO)₂}⁹–{Fe(NO)₂}⁹ complex (NO)₂Fe(μ‐SC₂H₄S)₂Fe(NO)₂]^2? ( 3 ) bridged by two terminal SC₂H₄S]^2? ligands. On the basis of the Fe K‐edge pre‐edge energy and S K‐edge XAS, the oxidation of complex 1 yielding (NO)₂Fe(S(CH₂)₃S)]^? is predominantly a metal‐based oxidation. The smaller S1‐Fe1‐S2 bond angle of 94.1(1)° observed in complex 1 (S1‐Fe1‐S2 88.6(1)° in complex 2 ), compared to the bigger bond angle of 100.9(1)° in the {Fe(NO)₂}⁹ DNIC (NO)₂Fe(S(CH₂)₃S)]^?, may be ascribed to the electron‐rich {Fe(NO)₂}¹⁰ DNIC preferring a restricted bite angle to alleviate the electronic donation of the chelating thiolate to the electron‐rich {Fe(NO)₂}¹⁰ core. The extended transition state and natural orbitals for chemical valence (ETS‐NOCV) analysis on the edt‐/pdt‐chelated {Fe(NO)₂}⁹ and {Fe(NO)₂}¹⁰ DNICs demonstrates how two key bonding interactions, that is, a Fe?S covalent σ bond and thiolate to the Fe d charge donation, between the chelating thiolate ligand and the {Fe(NO)₂}^9/10 core could be modulated by the backbone lengths of the chelating thiolate ligands to tune the electrochemical redox potential (E_1/2=?1.64 V for complex 1 and E_1/2=?1.33 V for complex 2 ) and to dictate structural rearrangement/chemical transformations (S‐Fe‐S bite angle and monomeric vs. dimeric DNICs).