Synthesis, Molecular Structure, and Vibrational Spectra of mer-Tris(carbonyl)iridium(III) Fluorosulfate, mer-Ir(CO)₃(SO₃F)₃

Abstract

Addition of carbon monoxide (0.5-2 atm) to iridium(III) fluorosulfate, Ir(SO(3)F)(3), dissolved in HSO(3)F over 4 days and at 60 degrees C, results in the quantitative formation of tris(carbonyl)iridium(III) fluorosulfate Ir(CO)(3)(SO(3)F)(3). Slow evaporation of the solvent produces single crystals of mer-Ir(CO)(3)(SO(3)F)(3). Crystal structure data for mer-Ir(CO)(3)(SO(3)F)(3): monoclinic, space group P2(1)/c, Z = 4, a = 8.476(1) Å, b = 12.868(2) Å, c = 12.588 (1) Å, beta = 108.24(1) degrees, V = 1304.0 Å(3), T = 200 K, R(F)() = 0.022 for 2090 data (I(o) >/= 2.5sigma(I(o))) and 200 variables. Vibrational spectra of the crystalline solid are consistent with a mer-isomer with CO stretching modes at 2249 (A(1)), 2208 (B(1)), and 2198 (A(1)) cm(-)(1) in the IR spectrum. In solution of HSO(3)F, additional CO stretching bands attributed to the fac-isomer are found in the FT-Raman and IR spectra at 2233 (A(1)) and 2157 cm(-)(1) (E). Additional evidence for a mixture of fac- and mer-isomers comes from (19)F NMR spectra. The vibrational spectra suggest strongly reduced iridium to CO pi-back-bonding. The crystal structure reveals significant intra- and intermolecular contacts between the electropositive C atom of the CO groups and O or F atoms of the fluorosulfate groups. Hence mer-tris(carbonyl)iridium(III) fluorosulfate becomes the first thermally stable, structurally characterized, and predominantly sigma-bonded carbonyl derivative of a metal in the +3 oxidation state.

Toward Visible-Light Photochemical CO2-to-CH4 Conversion in Aqueous Solutions Using Sensitized Molecular Catalysis

“…To confirm this hypothesis, we conducted infrared spectroscopy measurement (Figure S7), which revealed two vibrations at ca. 2255 and 2295 cm –1 , which closely match with CO vibration in Ir­(CO) x complexes. , Cyclic voltammetry (Figure S8) also revealed the apparition of an irreversible reduction wave at ca. −2 V vs SCE under CO, as previously observed …”

“…2255 and 2295 cm −1 , which closely match with CO vibration in Ir (CO) x complexes. 44,45 Cyclic voltammetry (Figure S8) also revealed the apparition of an irreversible reduction wave at ca. −2 V vs SCE under CO, as previously observed.…”

Activation of Aliphatic Ethers by TpMe2Ir Compounds: Multiple C−H Bond Activation and C−C Bond Formation

“…In this regard, comparison with other Ir(III) complexes with π-acceptor ligands is appropriate. For example, the tris(carbonyl) derivative Ir(SO 3 F) 3 (CO) 3 features a ν av (CO) of 2218 cm -1 , which is about 75 cm -1 higher than that found for gaseous CO (2143 cm -1 ), while in the mono(carbonyl) derivatives IrCl 3 (CO)(PR 3 ) 2 that contain the strongly basic trialkyl phosphines PEt 3 or PBu n 3 , ν(CO) appears in the proximity of 2000 cm -1 . Finally, the C(16)−O distance within the carbene fragment of 4b of 1.326(3) Å is short enough to suggest some double-bond character.…”

Enhanced Chemical and Electrochemical Water Oxidation Catalytic Activity by Hybrid Carbon Nanotube-Based Iridium Catalysts Having Sulfonate-Functionalized NHC ligands

“…The analysis is limited by the quality of the EXAS spectra, so the useful ranges were limited to Δ k ∼ 2.0–12.5 Å –1 and Δ R ∼ 1.1–3.9 Å. In order to elucidate the possible coordination of the O–SO 2 – groups to the metal center, phases and amplitudes for Ir–O–S paths (single and multiple scattering) were calculated from the X-ray diffraction crystal data of the fluorosulfate iridium­(III) compound, mer -[Ir­(CO) 3 (OSO 2 F) 3 ] . The addition of these paths does not allow accurate fits for the CNT-2-Ir spectra thereby suggesting that sulfonate group is not present in the Ir environment in the hybrid catalysts and that this position is occupied by oxygen groups on the nanomaterial wall as it was previously observed for CNT-1-Ir .…”