Synthesis, Structures, Spectroscopic and Electrochemical Properties of Dinitrosyl Iron Complexes with Bipyridine, Terpyridine, and 1,10-Phenathroline

Abstract

Three new dinitrosyl iron complexes LFe(NO) 2 (L = 2,2′-bipyridine (bipy) (1), 2,2′,2″-terpyridine (terpy) (2) and 1,10-phenathroline (phen) (3)) were synthesized by the reaction of Fe(NO) 2 (CO) 2 with corresponding ligands in THF. Complexes 1-3 were studied using IR, UV-vis, MS, NMR, and electrochemical techniques. Complexes 1 and 2 were also characterized using single crystal X-ray diffraction analysis. IR spectra of complexes 1-3 display two strong characteristic NO stretching frequencies (ν NO ) in the region reflecting donor properties of the ligands. Cyclic voltammetry studies show two quasi-reversible one-electron reductions for all complexes. Electrochemical investigations using different concentrations show that an irreversible one-electron reduction at −1.85 V for complex 2 and −1.80 V for complex 3 are from solvated species. Single-crystal X-ray structural analysis reveals that complex 1 crystallizes in triclinic P-1 space group and the asymmetric unit consists of one Fe(NO) 2 (bipy) molecule with the two NO groups located on two sides of Fe(bipy) plane. Complex 2 crystallizes in monoclinic P21/n space group and the asymmetric unit contains one Fe(NO) 2 (terpy) molecule, in which the NO groups are located on two sides of the plane consisted of Fe and two coordinated pyridyl rings, but almost parallel to the un-coordinated pyridyl ring. The crystal packings of both complexes 1 and 2 show intermolecular H-bonding and strong π−π stacking interactions.

Redox conversions of dinitrosyl iron complexes with natural thiol-containing ligands

“…[22]), the latter being fully identical to the EPR signal of reduced B-DNIC. In the paradigm of the initial electronic configuration ( Our conclusion concerning the ability of M-and B-DNIC to accept two electrons in each Fe(NO) 2 group in the course of their reduction is consistent with the electrochemical data [23,24]. The authors demonstrated that both forms of DNIC with various ligands (including thiol-containing ligands) exhibit two quasireversible one electron reductions.…”

Synthesis and structure of dinitrosyl iron complexes with secondary thiolate bridging ligands [Fe2(μ-SCHR2)2(NO)4], R = Me, Ph

“…The compounds were obtained by treatment of the mixture of iron pentacarbonyl with the corresponding thiol followed by addition of ethyl nitrite under inert atmosphere. 3 The formation of Roussin's red salt ester probably occurs via the stage of intermediate iron dinitrosyldicarbonyl Fe(NO) 2 (CO) 2 generation; this nitrosylated precursor is known to give DNICs when reacted with thiols [12,26] or with nitrogen containing bidentate aromatic ligands [38,39]. [19].…”

The Preparation, Structural Characteristics, and Physical Chemical Properties of Metal-Nitrosyl Complexes

“…Recently, we reported the synthesis, structures, and spectroscopic and electrochemical properties of three new dinitrosyl iron complexes with bidentate [N,N] chelating ligands; 2,2′-bipyridine, 14 , 2,2′,2′′-terpyridine, 15 , and 1,10-phenathroline, 16 [52]. Complexes 14–16 were prepared by mixing 1:1 ratio of Fe(NO) 2 (CO) 2 and the proper chelating ligands, bipy, terpy, and phen in THF and was stirred 48 h at room temperature under nitrogen atmosphere as shown in Scheme 3 (yields between 82 and 88%).…”