Insight into chalcogenolate-bound {Fe(NO)₂}⁹dinitrosyl iron complexes (DNICs): covalent characterversusionic character

Abstract

The synthesis, characterization and transformation of the thermally unstable {Fe(NO)2}9 dinitrosyl iron complex (DNIC) [(OMe)2Fe(NO)2]− (2) were investigated.

NO Reduction to N2O Triggered by a Dinuclear Dinitrosyl Iron Complex via the Associated Pathways of Hyponitrite Formation and NO Disproportionation

“…The crystallographic structure of complex 3 is depicted in Figure , and the selected bond distances and angles are presented in Table S1. The bond lengths of Fe–N­(O) range from 1.681(5) to 1.703(5) Å, and the N–O bond lengths are within 1.154(6)–1.174(6) Å, consistent with the published Fe–N­(O) and N–O bond lengths of {Fe­(NO) 2 } 9 DNICs. − It is noticed that complex 3 shows linkage isomers, that is, complex 3 with κ 2 - O , N -NO 2 linkage (O(5)–N(5)–O(6) (75%)) and complex 3 ′ with terminal η 2 - O -ONO linkage (O(5′)–N(5′)–O(6′) (25%)). Variable-temperature UV–vis spectra indicate that the linkage isomers of complex 3 with κ 2 - O , N -NO 2 and complex 3 ′ with η 2 - O -ONO are interconvertible, as shown in Figure S5.…”

Endogenous Conjugation of Biomimetic Dinitrosyl Iron Complex with Protein Vehicles for Oral Delivery of Nitric Oxide to Brain and Activation of Hippocampal Neurogenesis

“…After an aerobic degradation of DNIC-1 in SIF, the disappearance of S 1s →Fe 3d transition peaks, the shift of the S 1s →C–S σ* transition peak from 2474.8 to 2474.1 eV, and the formation of the S 1s →S–S σ* transition peak at 2472.6 eV indicate the conversion of Fe-bound [HOCH 2 CH 2 S] − ligands into released (SCH 2 CH 2 OH) 2 (Figure f). Moreover, the higher Fe K-edge pre-edge absorption energy at 7114.6 eV featured by the degradation byproducts supports the assembly of a ferric complex containing ionic ligands (i.e., phosphate, hydroxide, or oxide) after an aerobic degradation of DNIC-1 in SIF (Figure g). , On the basis of the characterization of the released NO and S/Fe K-edge XAS study, a slow oxidation of the [Fe­(μ-SR) 2 Fe] core within DNIC-1 under an aerobic condition initiates the transformation of bridging [HOCH 2 CH 2 S] − ligands into the released (SCH 2 CH 2 OH) 2 , which weakens the Fe-to-NO π-backbonding interaction to trigger the complete release of nitric oxide and the assembly of a ferric complex (Scheme S1a). , …”

“…Moreover, the higher Fe K-edge pre-edge absorption energy at 7114.6 eV featured by the degradation byproducts supports the assembly of a ferric complex containing ionic ligands (i.e., phosphate, hydroxide, or oxide) after an aerobic degradation of DNIC-1 in SIF (Figure 1g). 47,48 On the basis of the characterization of the released NO and S/Fe K-edge XAS study, a slow oxidation of the [Fe(μ-SR) 2 Fe] core within DNIC-1 under an aerobic condition initiates the transformation of bridging [HOCH 2 CH 2 S] − ligands into the released (SCH 2 CH 2 OH) 2 , which weakens the Fe-to-NO π-backbonding interaction to trigger the complete release of nitric oxide and the assembly of a ferric complex (Scheme S1a). 37,46 Upon incubation of DNIC-1 in SGFsp at 37 °C, the shortened half-life of 0.4 ± 0.1 h and the reduced release of ∼2 equiv of nitric oxide reveal a distinctive mechanism for an accelerated decay of DNIC-1 in SGFsp (Figure 1c−e,h).…”

Insight into the Electronic Structure of Biomimetic Dinitrosyliron Complexes (DNICs): Toward the Syntheses of Amido-Bridging Dinuclear DNICs

“…54 1). [38][39][40][42][43][44][45][46][47][48][49][50][51][52]56,57 In Fe K-edge XAS, the Fe 1s → Fe 3d preedge energy of Fe correlates with the oxidation state and effective nuclear charge of Fe (Z eff ), coordination geometries of the Fe center, and type of supporting ligands. 39,40,42,47,49,55,58 Therefore, tetrahedral complexes [Fe II (SPh) 4 ] 2− and [Fe III (SPh) 4 ] − were utilized as spectroscopic references to determine the oxidation state of Fe in {Fe(NO) 2 } 9 DNIC [(NO) 2 Fe(SPh) 2 ] − .…”

“…by the ionic Fe−OPh/Fe−OMe bonds, which will be further discussed in detail in section II.A.3. 51 Fe K-edge XAS can also be utilized to probe the electronic structure of {Fe(NO) 2 } 10 DNICs modulated by π-donor thiolate, σ-donor amine, and π-acceptor phosphine ligands. 42,49 Upon one-electron reduction of {Fe(NO) 2 } 9 [(NO) 2 Fe-(SEt) 2 ] − , a shift of the Fe 1s → Fe 3d preedge energies from 7113.5 to 7113.2 eV demonstrates the {Fe II (NO − ) 2 } 10 electronic structure of DNIC [(NO) 2 Fe(SEt) 2 ] 2− .…”