Two novel examples of hydroxylation of aromatic rings in coordination chemistry

Abstract

500 ns the difference spectrum evolves to a more resolved absorbance centered at 390 nm extending to 450 nm. This spectrum persists out to the maximum time delays obtainable (50-100 jus); notable is the fact that this spectrum is similar to that of TIH2 (see Figure 1). Time evolution of the absorbance at 390 and 460 nm is shown in Figure 2. At 460 nm a transient absorbance is noted; the transient decays to 20% of the initial value with a first-order rate constant k = 3.6 X 106 s"1 ( = 280 ns) and remains constant out to long times. At 390 nm an initial step is noted with the laser pulse followed by a grow in concurrent with the above decay. We attribute the 460-nm transient to the species TIH• as first a radical pair [TIH•, -D] and subsequently the free radical. The 390-nm absorbance appears due to both TIH• and TIH2, but primarily to the latter at long times.The laser flash experiments suggest that two pathways exist for formation of TIH2 from the radical pair formed via pho-( 19) Laser flash photolysis apparatus as described in ref 20, except a pulsed monitoring lamp was used.

Tailor made synthesis of amphiphilic azoaromatics via regioselective C–N bond fusion. Comparative studies of surface properties of the two positional isomers and cobalt complexes

“…Among these, the most recent and remarkable activities have been concentrated around the studies of the chemical transformations of the coordinated pap ligand via C-H activation. For example, novel type hydroxylation 7 and thiolation 8 reactions at the aromatic ring of the coordinated a Department of Inorganic Chemistry, Indian Association for the Cultivation of Science, Kolkata, 700 032. E-mail: icsg@iacs.res.in;Fax: +91-33-24732805;Tel: +91-33-24734971 b Department of Spectroscopy, Indian Association for the Cultivation of Science, Kolkata, 700 032 † Electronic supplementary information (ESI) available: ESI-MS spectra of [Co(L 1 ) 2 ]ClO 4 and [Co(L 5 )(L 1 )]ClO 4 (S1); 1 H NMR spectra of [Co(L 1 ) 2 ]ClO 4 (S2), HL 1 (S3a) and HL 2 (S3b); AFM topographical image of the single layer of HL 1 , transferred at 10 mN m -1 surface pressure (S4); FE-SEM image of the monolayer of [Co(L 1 )(L 5 )]ClO 4 at 10 mN m -1 surface pressure (S5); crystallographic parameters of [Co(L 1 )(L 5 )]ClO 4 •0.5C 6 H 14 (Table S1) are provided.…”

Status of Inorganic Chemistry Research in India

“…Thus, trans-bis(phenylazoacetaldoximato)platinum(II) was shown to undergo hydroxylation of the aromatic ring (Fig. 6) (Bandyopadhyay et al, 1983). His research group also contributed significantly to the (Pal et al, 2016), (Sinhababu et al, 2016), (Majumdar et al, 2018) (Dhara et al, 2018) (Pahar et al, 2018).…”

Cobalt-mediated direct and selective aromatic thiolation in the complex [CoIII(o-SC6H4NNC 5H4N)2]ClO4. Synthesis, spectroscopic characterisation and electron-transfer properties

“…On that basis we assume that in high-boiling dmf and in the presence of dithiocarbonate, complex 1 may be transformed into a four-membered orthometallated reactive intermediate A (Scheme 2) as a first step of the C᎐H bond activation of the phenyl ring. Orthometallations from the pendant phenyl ring of L 15 and related ligands such as diphenyldiazene, 16 diphenyldiazene thiol, 2 PhN᎐ ᎐ NC 6 H 3 (R)OH-2 2 and phenolic Schiff bases 2 are known. The insertion of sulfur, generated by cleavage of the carbon᎐sulfur bond of the dithiocarbonate, into the M᎐C σ bond of the reactive four-membered cyclometallated species A (if it exists) would eventually lead to the formation of B. Insertion of small molecules into the reactive M᎐C bond has been documented.…”