Copper coordinated ligand thioether-S and NO2− oxidation: relevance to the CuM site of hydroxylases. Issue 40 (22nd September 2015)

• Record Type: Journal Article
• Authors: Maji, Ram Chandra; Bhandari, Anirban; Singh, Ravindra; Roy, Suprakash; Chatterjee, Sudip K.; Bowles, Faye L.; Ghiassi, Kamran B.; Maji, Milan; Olmstead, Marilyn M.; Patra, Apurba K.
• Is Part Of: Dalton transactions. Volume 44:Issue 40(2015)
• Page Start: 17587
• Page End: 17599
• Publication Date: 2015-09-22
• Subjects: Chemistry, Inorganic -- Periodicals; Chemistry, Physical and theoretical -- Periodicals; Chemistry, Inorganic -- Periodicals; 546.05
• DOI: 10.1039/c5dt02184g
• Languages: English
• ISSNs: 1477-9226

Abstract

Abstract : Cu II mediated systematic and stoichiometric oxidation of aryl thioether-S and NO2 − using the oxidants H2 O2 and molecular O2 . Abstract : In order to gain insight into the coordination site and oxidative activity of the CuM site of hydroxylases such as peptidylglycine α-hydroxylating monooxygenase (PHM), dopamine β-monooxygenase (DβM), and tyramine β-monooxygenase (TβM), we have synthesized, characterized and studied the oxidation chemistry of copper complexes chelated by tridentate N2 Sthioether, N2 Osulfoxide or N2 Osulfone donor sets. The ligands are those of N -2-methylthiophenyl-2′-pyridinecarboxamide (HL1 ), and the oxidized variants, N -2-methylsulfenatophenyl-2′-pyridinecarboxamide (HL1 SO ), and N -2-methylsulfinatophenyl-2′-pyridinecarboxamide (HL1 SO2 ). Our studies afforded the complexes [(L1)Cu II (H2 O)](ClO4 )·H2 O (1 ·H2 O), {[(L1 SO )Cu II (CH3 CN)](ClO4 )} n (2 ), [(L1)Cu II (ONO)] (3 ), [(L1 SO )Cu II (ONO)] n (4 ), [(L1)Cu II (NO3 )] n (5 ), [(L1 SO )Cu II (NO3 )] n (6 ) and [(L1 SO2 )Cu II (NO3 )] (7 ). Complexes1 and3 were described in a previous publication ( Inorg. Chem., 2013, 52, 11084). The X-ray crystal structures revealed either distorted octahedral (in2, 4–6 ) or square-pyramidal (in1, 3 ) coordination geometry around Cu II ions of the complexes. In the presence of H2 O2, conversion of1 →2, 3–5 →6 and6 →7 occurs quantitatively via oxidation of thioether-S and/or Cu(ii ) coordinated NO2 − ions. Thioether-S oxidation of L1 also occurs when [L1] − is reacted with [Cu I (CH3 CN)4 ](ClO4 ) in DMF under O2, albeit low in yield (20%). Oxidations of thioether-S and NO2 − were monitored by UV-Vis spectroscopy. Recovery of the sulfur oxidized ligands from their metal complexes allowed for their characterization by elemental analysis, 1 H NMR, FTIR and mass spectrometry.