Formation and Characterization of the Photochemically Interconvertible Side-On and End-On Bonded Dioxygen−Iron Dioxide Complexes in Solid Argon

Abstract

Two interconvertible iron dioxide-dioxygen complexes were prepared and characterized by matrix isolation infrared absorption spectroscopy as well as theoretical calculations. Iron atoms react with O2 to form the inserted FeO2 molecule in solid argon only upon UV-visible light irradiation. Annealing allows the dioxygen molecules to diffuse and to react with FeO2 and form the side-on and end-on bonded dioxygen-iron dioxide complexes, (eta2-O2)FeO2 and (eta1-O2)FeO2. The side-on bonded structure is a peroxide complex having a singlet ground state with a nonplanar C2v symmetry. The end-on bonded isomer is characterized to be a superoxide complex with a planar 3A' ' ground state. These two isomers are photoreversible, that is, near-infrared light (lambda > 850 nm) induces the conversion of the side-on bonded (eta2-O2)FeO2 complex to the end-on bonded (eta1-O2)FeO2 isomer and vice versa with red light irradiation (lambda > 600 nm).

Metal Cluster Models for Heterogeneous Catalysis: A Matrix‐Isolation Perspective

“…[95,106] Furthermore,m any of the monoxides and dioxides have been found to add furtherO 2 units. Complexes MO(O 2 )o ft he monoxides MO with one O 2 ,m ostly with side-on coordination, have been observed for M = Sc, [45,46] Y, [47] La, [47] Ti, [56] Zr, [57] Hf, [57] Mn, [70] Fe, [73,76] Ni, [91] Pt, [92] and likelya lso for Co [80] and Rh. [81] For Ti,t he TiO(O 2 ) 2 complex is also observed.…”

“…[56] For Sc, Y, and La, ozonide complexes MO(O 3 )h ave also been generated. [48,49] Complexes MO 2 (O 2 )o ft he dioxides MO 2 with one O 2 have been found for M = V, [58,60] (tentatively Cr, [66] )M n, [70,72] Fe, [73,76,78] Co, [84] Ni, [91] Zn, [104] Nb, [59,61] Mo, [65] Ru, [71] Rh, [81] Cd, [104] La, [49] Ta , [59,61] W, [66] Re, [71] Os, [71] and Ir, [82,87] mostly with side-on coordinated O 2; and in somec ases with end-on coordination. For example, iron atoms react by UV/Vis irradiation with O 2 to yield the FeO 2 dioxide, which by annealinga ttaches another O 2 to form the FeO 2 (O 2 )c omplex.…”

“…For example, iron atoms react by UV/Vis irradiation with O 2 to yield the FeO 2 dioxide, which by annealinga ttaches another O 2 to form the FeO 2 (O 2 )c omplex. [76] Similarly,c obalt atoms react by UV/Vis irradiation with O 2 to yield the CoO 2 dioxide, which by annealing forms CoO 2 (O 2 ). [84] Interestingly,inthe latter case, annealing leads at first to the metastable end-on CoO 2 (OO) complex, which then slowly transforms into the side-on CoO 2 (O 2 ) complex (Scheme 5).…”

A Matrix‐Isolation and Quantum‐Chemical Investigation of FeF4

“…[3] Beyond these anionic complexes, neutral iron oxides, such as [O 2 Fe(h 2 -O 2 )], have been stabilized under cryogenic conditions in rare gas matrices. [4] Furthermore, iron nitrido complexes in the + 5 and + 6 oxidation states have been successfully prepared in solution at low temperatures, as shown by Mçssbauer and X-ray absorption spectroscopy. [5,6] Despite a long history of research in this field, only a few binary iron halides are known.…”

Water Adsorption on Platinum Dioxide and Dioxygen Complex: Matrix Isolation Infrared Spectroscopic and Theoretical Study of Three PtO2–H2O Complexes

“…Note that both the observed OÀO stretching frequency and the predicted OÀO bond length suggest that the O 2 ligand in complex B is due to a peroxide dianion with an OÀO single bond. [42,43] Previous experimental studies on the adsorption of water and molecular oxygen on single-crystal platinum surface showed no evidence for the cleavage of H 2 O upon adsorption, and the presence of molecular oxygen has no influence on water adsorption process. [44] Consistent with the results from surface chemistry studies, the platinum atoms were found to be inert toward water molecule in solid argon, and no water dissociation product was detected in the reaction of platinum atoms and H 2 O in the presence of O 2 .…”