abstract
Iron catalyzed carbon-nitrogen bond formation reactions of a wide variety of nucleophiles and aryl halides using well-defined iron-complexes featuring redox noninnocent 2-(arylazo)-1,10-phenanthroline (L-1) ligands are reported. Besides substrate centered C-N coupling, C-N bond formation reactions were also observed at the ortho- and para-positions of the phenyl ring of the coordinated azo-aromatic scaffolds affording new tetradentate ligands, 2-N-aryl-(2-arylazo)-1,10-phenanthroline (L-2), and tridentate ligands, 4-N-aryl-(2-arylazo)-1,10-phenanthroline (L-3), respectively. Control experiments and mechanistic studies reveal that the complex [(FeLCl2)-Cl-1] (1) undergoes in situ reduction during the catalytic reaction to produce the monoanionic complex [1](-), which then acts as the active catalyst. The metal (iron) and the coordinated ligand were found to work in a cooperative manner during the transfer processes involved in the fundamental steps of the catalytic cycle. Detailed experimental and theoretical (DFT) studies were performed to get insight into the competitive substrate versus ligand centered amination reactions.
keywords
ANTI-MARKOVNIKOV HYDROAMINATION; ANION-RADICAL COMPLEXES; ELECTRON-TRANSFER; ARYL CHLORIDES; CARBENE RADICALS; DIRECT ARYLATION; CROSS-COUPLINGS; RING AMINATION; H AMINATION; REDOX
subject category
Chemistry
authors
Sinha, S; Sikari, R; Sinha, V; Jash, U; Das, S; Brandao, P; Demeshko, S; Meyer, F; de Bruin, B; Paul, ND
our authors
Paula Cristina Ferreira da Silva Brandão
Assistant Researcheracknowledgements
DST (Project: YSS/2015/001552) supported the present research. S.S. acknowledges IIESTS, R.S. acknowledges RGNF, U.J. acknowledges DST-Inspire, S.D. acknowledges UGC for fellowship. Financial Support from IIESTS is duly acknowledged. We sincerely thank Asish Kr. Singha Deb, Scientific Officer, BARC, Trombay, Mumbai 400 085, India, for carrying out the ICPMS and ICPOES experiments. P.B. thanks CICECO-Aveiro Institute of Materials, POCI-01-0145-FEDER-007679 (FCT ref. UID/CTM/50011/2013), financed by national funds through the FCT/MEC and when appropriate cofinanced by FEDER under the PT2020 Partnership Agreement. V.S. and B.d.B. acknowledge support from the Research Priority Area Sustainable chemistry of the University of Amsterdam, and the Industrial Partnership Programme (IPP) Computational Sciences for Energy Research (project 13CSER003), which is financially supported by The Netherlands Organization for Scientific Research (NWO) and is cofinanced by Shell Global Solutions International B.V. The calculations were carried out on the Dutch national e-infrastructure with the support of the SURF cooperative. S.D. and F.M. thank the University of Gottingen for support. Use of the single crystal X-ray facility at SAIF-IIESTS is duly acknowledged.