EPR study of paramagnetic rhenium(I) complexes (bpy>>·>>−>>)Re(CO)3X relevant to the mechanism of electrocatalytic CO2 reduction †

Abstract

In situ reduction of (bpy)Re(CO) 3 Cl, bpy = 2,2Ј-bipyridine, at a platinum cathode under CO 2 atmosphere in acetonitrile or acetone has produced a series of distinct EPR spectra which are attributed to (bpy Ϫ ) containing species and which invariably reveal the interaction of the unpaired electron with the metal nuclei ( 185,187 Re, I = 5/2). The EPR investigation of various model complexes (bpy Ϫ )Re(CO) 3 X, generated by electrochemical reduction under argon of diamagnetic precursors (bpy)Re(CO) 3 X, X = Cl Ϫ , CF 3 SO 3 Ϫ , CH 3 O Ϫ , H Ϫ , tetrahydrofuran, CH 3 CN, CO, HCO 2 Ϫ , HCO 3 Ϫ and CH 3 C(O) Ϫ has been used to interpret the results from the reactions under CO 2 atmosphere. Paper 7/02467C

Insertion of Unsaturated Organic Electrophiles into MolybdenumAlkoxide and RheniumAlkoxide Bonds of Neutral, Stable Carbonyl Complexes

“…Previous preparations of [Re(OCH 3 )(CO) 3 (bipy)] involve the reaction of [Re(NCMe)(CO) 3 (bipy)]PF 6 (in turn prepared by refluxing [ReCl(CO) 3 (bipy)] with AgPF 6 in CH 3 CN for eight hours) with two equivalents of sodium methoxide in methanol (reaction time: 17 hours, yield: 42 %) [8] and the Scheme 1. Synthesis of the alkoxo complexes.…”

Structure, electrochemistry, spectroscopy, and magnetic resonance, including high-field EPR, of {(μ-abpy)[Re(CO)3X]2}o/•−, where abpy=2,2′-azobispyridine and X=F, Cl, Br, I

“…Complexes (N-N)Re(CO) 3 X, X = halogen, with unsaturated a-diimine chelate ligands (N-N), including 2,2 0 -bipyridine or 1,10-phenanthroline, have raised attention because of their photoemission [1], their energy and charge transfer properties [2], and their photo-and electrocatalytic activity, especially in the reduction of CO 2 [3][4][5][6]. The involvement of intermediates containing the radical anion (N-N) À in both the MLCT excited states, [(N-N) À Re II (CO) 3 X] * [1,2], and in the electrocatalytic cycles [3,6] has prompted studies of the electrochemistry, spectroscopy [7] and spectroelectrochemistry (IR, UV-VIS, EPR) of systems [(N-N)Re(CO) 3 X] À [8][9][10][11][12] with ''18+d" valence electron configuration [8a].…”

A complete series of tricarbonylhalidorhenium(I) complexes (abpy)Re(CO)3(Hal), Hal=F, Cl, Br, I; abpy=2,2′-azobispyridine: Structures, spectroelectrochemistry and EPR of reduced forms

“…Since the discovery that (bpy)Re(CO) 3 Cl can act as an efficient electrocatalyst for the reduction of CO 2 [1,2] many complexes of the type (N Ù N)Re(CO) 3 (Hal) with N Ù N = a-diimine or related chelate ligand have been the subject of studies in the context of photoor electrocatalyzed CO 2 reduction [3][4][5]. The primary activation mechanism involves the addition of an electron to the p * orbital of the N Ù N ligand with the result of a labilization of the halide as essential step [5][6][7].…”

“…The primary activation mechanism involves the addition of an electron to the p * orbital of the N Ù N ligand with the result of a labilization of the halide as essential step [5][6][7].…”