Dioxygen uptake and transfer by Co(III), Rh(III) and Ir(III) catecholate complexes

The Organometallic Chemistry of Rh‐, Ir‐, Pd‐, and Pt‐Based Radicals: Higher Valent Species

“…The spectra of both species are consistent with a distorted square-pyramidal geometry. The structure of these species seems to be similar to that of the related Ir(II) complex [Ir II (DTBC)(P 3 -ligand)] (DTBC ¼ 3,5-di-tert-butylcatecholate), revealing comparable EPR parameters (195). The presence of two isomeric species was explained by assuming different Jahn-Teller distortions related to the asymmetry of the ligand.…”

“…Since only weak EPR signals centered $ g ¼ 2.00 were observed, the spin-trap reagent 2-methyl-2-nitrosopropane (t-BuÀ ÀNO) was used. At 240 K hyperfine coupling with a N atom (44 MHz) with 195 Pt satellites (112 MHz) was observed. The g-value of 2.0060 is clearly influenced by spin-orbit coupling (platinum influence).…”

“…The g-value of 2.0060 is clearly influenced by spin-orbit coupling (platinum influence). Both the g value and a 195 Pt coupling suggest that the spin trap has intercepted the organometallic product of the photopromoted homolytic PtÀ ÀC bond splitting reaction (123). Apparently, the spin trap is less effective to capture the methyl radical.…”

Functional models for catechol dioxygenases: Iron(III) complexes of cis-facially coordinating linear 3N ligands

“…The cis-facial coordination allows both O 2 and substrate to occupy the face opposite to L to form the intermediate [53] [(L)(DBSQ)Fe(II)-O 2 ] À that leads to the extradiol products. (The proposed intermediate resembles the crystallographically characterized ½IrÀðO 2À 2 ÞÀðPPh 3 Þ 3 ðDBCÞ species, which yields the extradiol product [52].) In contrast, only the intradiol cleavage product 3,5-di-tert-butyl-1-oxocyclohepta-3,5-diene-2,7-dione (20%) was observed [32] when L in [FeL(DBC)Cl] is the meridionally coordinated 2,2 0 :6 0 2 00 -terpyridine.…”

Chloro[o-(diphenylphosphino)benzaldehyde]{N-[o-(diphenylphosphino)benzylidene]ethylamine}(tetrachloro-o-catecholato)iridium(III)

“…In spite of minor structural differences, the trends are similar in the two independent molecules. The Ir--O distances are in the expected range for IrnI--catecholate complexes (Barbaro et al, 1992). The Ir--O linkage trans to the Ir--P linkage is significantly longer than that trans to the Ir--C1 linkage [2.09 (1) versus 2.06(1)/~ and 2.11(I) versus 2.04(2)A, in the two molecules, respectively].…”