Synthesis and Characterization of Iridium(V) Coordination Complexes With an N,O‐Donor Organic Ligand

Abstract

We have prepared and fully characterized two isomers of [Ir IV (dpyp) 2 ]( dpyp = meso-2,4-di(2-pyridinyl)-2,4pentanediolate). These complexes can cleanly oxidizet o [Ir V (dpyp) 2 ] + ,w hicht oo ur knowledge represent the first mononuclear coordination complexes of Ir V in an N,O-donor environment. One isomer has been fully characterized in the Ir V state,i ncluding by X-rayc rystallography,X PS,a nd DFT calculations,a ll of which confirm metal-centered oxidation. The unprecedented stability of these Ir V complexes is ascribed to the exceptional donor strength of the ligands,their resistance to oxidative degradation, and the presence of four highly donor alkoxide groups in aplane,which breaks the degeneracy of the d-orbitals and favors oxidation.

An Ir/Ni(OH)2 Heterostructured Electrocatalyst for the Oxygen Evolution Reaction: Breaking the Scaling Relation, Stabilizing Iridium(V), and Beyond

“…The binding energies of the Ir 4f 7/2 peaks are 61.1, 62.4, and 64.3 eV, which correspond to metallic Ir, Ir (IV), and the satellite peak of Ir(IV), respectively. [ 37,38 ] Compared with pure Ir NPs, not only are the binding energies of Ir positively shifted, but the proportion of Ir(IV) species is also significantly increased, indicating the electron transfer from Ir NPs to Ni(OH) 2 as well as the possible formation of IrO bonds at the heterointerface. [ 39 ] In the meantime, such electron transfer leads to a negative shift for the Ni 2p binding energy after the hybridization, and the binding energy of Ni 2p 3/2 decreases from 856.2 to 854.5 eV (Figure S5, Supporting Information).…”

“…[35,36] Two additional doublets can be found in the higher binding energy region, and the peak positions indicate the existence of Ir(IV). [37,38] Nevertheless, the relative peak area ratio reveals that the Ir NPs primarily consist of metallic Ir with minor surface oxides. For the Ir/Ni(OH) 2 heterostructure, the Ir 4f spectrum can be fitted with three doublets (Figure 2b; Table S1, Supporting Information).…”

Concerted proton-electron transfer oxidation of phenols and hydrocarbons by a high-valent nickel complex

“…These g values, as well as g ave ¼ 2.145, are consistent with a lowspin square-planar d 7 Ni(III) complex. 15 As demonstrated for a variety of iridium complexes, [16][17][18][19] X-ray photoelectron spectroscopy (XPS) provides another method for identifying a metal-centered oxidation. For metal-centered redox events with no change to the ligand set, the binding energy is expected to increase with oxidation state.…”

“…29 Hammett analysis showed that k 2 decreases with the electron-withdrawing capabilities of the para-substituent of the substrate (r ¼ À2. 19). This result is inconsistent with a rate-limiting proton transfer followed by electron transfer (PT-ET) mechanism, which would show a positive linear correlation in the Hammett plot.…”

Photochemically deposited Ir-doped NiCo oxyhydroxide nanosheets provide highly efficient and stable electrocatalysts for the oxygen evolution reaction

“…4a, two main peaks of Ir 4f 7/2 and Ir 4f 5/2 can be deconvoluted into Ir 3+ and Ir 4+ [37], and two bands at 61.8 and 64.9 eV correspond to Ir 3+ , while the Ir 4+ peaks are located at 62.8 and 65.8 eV. But after OER, the spectrum shows a significant shift toward higher binding energy, which indicates that some of the Ir 3+ /Ir 4+ have been further oxidized to Ir 5+ species [38][39], which is consistent with the results of the CV test in Fig. 5c.…”