Influence of the cation on the properties of binuclear iron nitrosyl complexes. Synthesis and crystal structure of [Pr4 nN]2[Fe2S2(NO)4]

Abstract

The binuclear nitrosyl complexes Q2[Fe2S2(NO)4], where Q = Me, Et, Pr n. and Bu n, were synthesized. The crystals of [Pr]N 12Fe2S2(NO)a were studied by X-ray analysis. The influence of the cation size on the electronic structure and symmetry of its local environment in the synthesized complexes was examined. The decrease in the isomeric shifts in the 57Fe Mbssbauer spectra is related to the increase in the length of the alkyt substituent chain of the quaternary tetraammonium cation and is consistent with changing the structural parameters: a decrease in the bond angle of the Fe--NO bond and stretching vibrations of the NO groups due to changes in intermolecular contacts.

Synthesis, structure, biochemical, and docking studies of a new dinitrosyl iron complex [Fe2(μ-SC4H3SCH2)2(NO)4]

“…The presence of one main doublet (Fig. S1) shows the identity of the two iron atoms in the complexes, and it is consistent with the known data for diamagnetic binuclear iron complexes [35,29]. The validity of these data is also supported by the Mulliken charge analysis.…”

Insight into the Dinuclear {Fe(NO)2}10{Fe(NO)2}10 and Mononuclear {Fe(NO)2}10 Dinitrosyliron Complexes

“…According to the absence of the EPR signal and the lower Fe K-edge preedge energy 7113.2 eV (vs 7113.4 and 7113.8 eV for rRRE-S t Bu and [(NO) 2 Fe(μ-S t Bu)] 2 , respectively), , the electronic structure of the {Fe(NO) 2 } 10 ­{Fe(NO) 2 } 10 core of com­plex 2 is best de­scribed as {Fe II (NO – ) 2 } 10 ­{Fe II (NO – ) 2 } 10 . ,, This study, including certain results from earlier studies, demonstrates that the binding affinity of ligands ([SR] − (R = alkyl) and [OPh] − ) toward {Fe(NO) 2 } 9/10 and {Fe(NO) 2 } 9/10 {Fe(NO) 2 } 9/10 motifs, respectively, is in the order of [SR] − > [OPh] − . It may rationalize that most of the DNICs and RREs characterized and proposed nowadays are bound to protein through cysteinate side chains in biology. , As indicated in Chart , the dinuclear DNICs can be classified according to oxidation levels and configurations: (a) the EPR-silent neutral {Fe(NO) 2 } 9 {Fe(NO) 2 } 9 RRE, (b) the EPR-active neutral {Fe(NO) 2 } 9 {Fe(NO) 2 } 9 RRE containing two separate {Fe(NO) 2 } 9 motifs, (c) the EPR-silent anionic {Fe(NO) 2 } 9 {Fe(NO) 2 } 9 RRE containing mixed thiolate–sulfide-bridged ligands, (d) the EPR-silent {Fe(NO) 2 } 9 {Fe(NO) 2 } 9 Roussin’s red salt, (e) the EPR-active {Fe(NO) 2 } 10 {Fe(NO) 2 } 9 reduced RREs, and (f) the EPR-silent {Fe(NO) 2 } 10 {Fe(NO) 2 } 10 dianionic reduced RREs.

1

The {Fe(NO) 2 } 10 DNIC 3 and the {Fe(NO) 2 } 9 DNIC [K-18-crown-6 ether][(NO) 2 Fe(SEt) 2 ] are chemically interconvertible without decomposition. On the basis of IR ν NO stretching frequencies, Fe–N (N–O) bond distances and Fe K-edge preedge energy of DNIC 3 , the electronic structure of {Fe(NO) 2 } 10 core of DNIC 3 is best described as {Fe II (NO – ) 2 } 10 .…”

Coordination and Organometallic Chemistry of Metal−NO Complexes

“…720 From an inorganic perspective, the archetypal iron sulfur nitrosyl complexes are Roussin's black ([Fe 4 (NO) 7 S 3 ] -) and red ([Fe 2 -(NO) 4 S 2 ] 2-) salts, so named after their discoverer and colors. The correlation of the counterion size on the solid-state molecular structures and Mo ¨ssbauer spectra of both varieties of Roussin's salts have been established, [721][722][723] and the selenium analogue of Roussin's black salt has been structurally characterized. 724 Furthermore, both salts have been investigated for their photolytic, [725][726][727] electrochemical, 728 and biological [729][730][731][732] properties.…”