Diiridium Bimetallic Complexes Function as a Redox Switch To Directly Split Carbonate into Carbon Monoxide and Oxygen.

A pair of diiridium bimetallic complexes exhibit a special type of oxidation-reduction reaction that could directly split carbonate into carbon monoxide and molecular oxygen via a low-energy pathway needing no sacrificial reagent. One of the bimetallic complexes, Ir(III)(µ-Cl)2Ir(III), can catch carbonato group from carbonate and reduce it to CO. The second complex, the rare bimetallic complex Ir(IV)(µ-oxo)2Ir(IV), can react with chlorine to release O2 by the oxidation of oxygen ions with synergistic oxidative effect of iridium ions and chlorine atoms. The activation energy needed for the key reaction is quite low (∼20 kJ/mol), which is far less than the dissociation energy of the C═O bond in CO2 (∼750 kJ/mol). These diiridium bimetallic complexes could be applied as a redox switch to split carbonate or combined with well-known processes in the chemical industry to build up a catalytic system to directly split CO2 into CO and O2.

Water attack umpolung aromatic systems to release hydrogen.

The synthesis and structures of a series of cyclometalated iridium(III) complexes based on benzoxazole derivatives and triphenylphospine are reported. These complexes have a general formula (C^N)(2)Ir(Cl)(pph(3)) [where C^N is a monoanionic cyclometalating ligand, dfpbo = (difluorophenyl)benzoxazolato, pbo = 2-phenylbenzoxazolato, nbo = 2-(2-naphthyl)benzoxazolato, and pph(3) is a triphenylphospine ligand]. The complexes (dfpbo)(2)Ir(Cl)(pph(3)) (2a), (pbo)(2)Ir(Cl)(pph(3)) (2b), and (nbo)(2)Ir (Cl)(pph(3)) (2c) have been structurally characterized by X-ray crystallography. Complex 2a shows facile umpolung in the phenyl rings of the arylphosphine ligand and displays a catalytic propensity for water splitting.

An 18+δ iridium dimer releasing metalloradicals spontaneously.

Reductive elimination of a bridged chlorine from a diiridium(iii) core, [(dfpbo)(2)Ir(µ-Cl)](2) (dfpbo = 2-(3.5-difluorophenyl)benzoxazolato-N,C(2)), afforded an iridium dimer, [(fpbo)(2)Ir](2)(µ-Cl), showing an 18+δ structure with a bent bridge, which can release metalloradicals spontaneously in solution at room temperature.

A novel cyclometalated dimeric iridium complex, [(dfpbo)2Ir]2 [dfpbo = 2-(3,5-difluorophenyl)benzoxazolato-N,C2'], containing an unsupported Ir(II)-Ir(II) bond.

An unusual iridium complex, [(dfpbo)(2)Ir](2) [dfpbo = 2-(3,5-difluorophenyl)benzoxazolato-N,C(2')], which is the first dimeric iridium complex composed of two bis-cyclometalated Ir(II) structures connected by an unsupported Ir(II)-Ir(II) bond, has been synthesized and fully characterized. Under mild conditions of neutral pH at room temperature, this complex dissociated spontaneously to form the stable radical [Ir(dfpbo)(2)]*.