872415-81-1Relevant academic research and scientific papers
Base-promoted selective aryl C-Cl cleavage by iridium(III) porphyrins via a metalloradical ipso addition-elimination mechanism
Cheung, Chi Wai,Chan, Kin Shing
, p. 4999 - 5009 (2011)
Base-promoted aryl carbon-chlorine bond (Ar-Cl) cleavage by iridium(III) porphyrin carbonyl chloride (IrIII(ttp)(CO)Cl; ttp = 5,10,15,20-tetrakis(p-tolyl)porphyrinato dianion) was achieved in the presence of K2CO3 to give iridium(III) porphyrin aryls (Ir III(ttp)Ar). Mechanistic studies revealed that K2CO 3 promotes the reduction of Ir(ttp)(CO)Cl to give the iridium(II) porphyrin dimer intermediate [IrII(ttp)2. [Ir(ttp) 2 is the source of IrII(ttp) metalloradical, which cleaves Ar-Cl to give Ir(ttp)Ar and a chlorine radical (Cl?) via radical ipso substitution in an addition-elimination pathway. Cl ? reacts with [Ir(ttp)2 to yield Ir(ttp)Cl for subsequent base-promoted reduction and Ir(ttp) for radical chain propagation. Additionally, the base-promoted Ar-Cl cleavage of chlorobenzene (PhCl) by Ir(ttp)(CO)Cl gives both Ir(ttp)Ph and 1,4-bis-iridium(III)-porphyrin benzene, IrIII(ttp)(p-C6H4)IrIII(ttp). The reactive Cl? can simultaneously react with PhCl via homolytic aromatic substitution to give 1,4-dichlorobenzene, which further undergoes double Ar-Cl cleavage to form Ir(ttp)(p-C6H4)Ir(ttp).
Development of iridium porphyrin arrays by axial coordination through N-bidentate ligand: Synthesis and evaluation of the optical, electrochemical and thermal properties
Castro, M. Cidália R.,de Sá, Arsénio,Fonseca, António M.,Raposo, M. Manuela M.,Machado, Ana V.
, p. 302 - 308 (2018)
Several organic compounds have been used in optoelectronics devices; porphyrins, due to their interesting optical and electronic properties, have shown an attractive potential to be used on molecular electronics. Among other advantages, porphyrins easily coordinate with several metal ions, which allows the assembly with peripheral or axial ligands introducing new properties to the supramolecular porphyrin. In this work, a new metalloporphyrin system with 5,10,15,20-(tetra-p-tolyl)porphyrin (ttp) and iridium(III) where 4,4′-bipyridine (bpy) coordinate in the axial positions was successfully synthetized, through the formation of “shish kebab” structures. This new compound was characterized through ultraviolet–visible, proton nuclear magnetic resonance, Fourier-transform infrared and Raman spectroscopies, thermogravimetry, differential scanning calorimeter and cyclic voltammetry. The introduction of the bpy on the metalloporphyrin moiety exhibited important influence on the optical, thermal and electrochemical properties.
Selective oxidation of (porphyrinato)iridium(III) arylethyls by nitroxide: Evidence for stabilization of carbon-centered Ir-CH2-CHR radicals by iridium
Yeung, Siu Kwan,Chan, Kin Shing
, p. 6426 - 6430 (2008/10/09)
(Arylethyl)iridium(III) porphyrins were oxidized selectively with excess 2,2,6,6-tetramethylpiperidinoxy (TEMPO) at the benzylic positions to yield (2-aryl-2-oxoethyl)iridium porphyrins. Other alkyl- and PhCH2CH 2CH2-substituted iridium porphyrins did not react or gave complex mixtures and low yields of indium methyl. The proposed intermediate of the carbon-centered IrIII(CH2CHR) radical is probably stabilized by the β iridium center, allowing the (slipped) olefin metalloradical complex IrII(CH2=CHR) as a reasonable resonance structure.
