Synthesis and Catalysis of Redox‐Active Bis(imino)acenaphthene (BIAN) Iron Complexes. Issue 16 (10th July 2017)

• Record Type: Journal Article
• Authors: Villa, Matteo; Miesel, Dominique; Hildebrandt, Alexander; Ragaini, Fabio; Schaarschmidt, Dieter; Jacobi von Wangelin, Axel
• Is Part Of: ChemCatChem. Volume 9:Issue 16(2017)
• Page Start: 3203
• Page End: 3209
• Publication Date: 2017-07-10
• Subjects: electrochemistry -- hydrogenations -- imines -- iron -- redox-active ligands; Catalysis -- Periodicals; 541.39505
• DOI: 10.1002/cctc.201700144
• Languages: English
• ISSNs: 1867-3880

Abstract

Abstract: Reactions of various substituted bis(imino)acenaphthenes (R‐BIANs) with FeCl2 (thf)1.5 afforded the tetrahedral complexes (R‐BIAN)FeCl2 (2 ) from bulky α‐diimines and the octahedral complexes [Fe(R‐BIAN)3 ][FeCl4 ]2 (3 ) from less bulky ligands. The driving force for the formation of complexes3 is the high ligand‐field stabilization of the low‐spin Fe II center. The two sets of complexes exhibit distinct charge‐transfer band intensities and redox activities. (R‐BIAN)FeCl2 complexes showed reversible ligand‐centered reductions at −0.9 V (vs. FcH/FcH + ; FcH: ferrocene); further reduction led to decomposition. Irreversible oxidations were observed at 0.2 and 0.4 V, associated with a reduction at −0.4 V, as well as a ligand‐centered redox event at 1.0 V. First applications of the Fe(BIAN) complexes to hydrogenations of alkenes indicated good catalytic activity under mild conditions. Abstract : Ironing out ligand differences : A set of redox‐active tetrahedral and octahedral bis(imino)acenaphthene (BIAN) iron(II) complexes was prepared and fully characterized. The complexes exhibited reversible BIAN‐centered 1 e − reductions and could be applied to catalytic hydrogenations of bulky alkenes upon reductive activation.