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Unformatted text preview: Project Werner Report February 11, 2011 S y n th e s is a n d C h a ra c te riza tio n o f Iro n D e riv a tiv e s H a v in g a P y rid in e-L in k e d B is (a n ilid e ) P in c e r L ig a n d Edw ard C. W eintrob, Daniel Tofan, and John E. Bercaw * Arnold and M abel Beckm an Laboratories of C hem ical Synthesis, C alifornia Institute of Technology, Pasadena, C alifornia 91125 Received January 15, 2009 A pyridine-linked bis(aniline) pincer ligand, [ 2 ]H 2 ([ 2 ]H 2 ) (2,6-NC 5 H 3 (2-(2,4,6-M e 3 C 6 H 2 )-NHC 6 H 4 ) 2 ), has been synthesized in two steps. Deprotonation with M e 3 SiCH 2 Li followed by m etalation with FeCl 2 yielded a LiCl adduct of [ 2 ]Fe. The com plex is freed of LiCl with excess TlPF 6 or by crystallization from toluene/petroleum ether, giving [ 2 ]Fe(THF). [ 2 ]Fe(THF) reacts with I 2 and O 2 to generate [ 2 ]FeI and ([ 2 ]Fe) 2 O , respectively. The com plexes have been characterized by 1 H NM R spectroscopy, elem ental analysis, X-ray crystallography, and UV- vis spectroscopy. [ 2 ]Fe(THF) has been exam ined using cyclic voltam m etry. Introduction N oble m etals have been dom inant in m any areas of catalytic organic transform ations: a fact that m ay be partially due to their readily accessible tw o electron redox couples, as w ell as their oxygen, w ater, and functional group tolerance. 1 These abilities are counterbalanced, how ever, by those sam e m etals cost, and in som e cases by environm ental or toxicological considerations. B y com parison, iron is cheap, relatively nontoxic, and environm entally benign. 2 For these reasons, this decade has seen an em ergence of research in areas not historically associated w ith iron, 3- 6 including hydrogenation, 7- 13 hydrosilation, 8 hydrodefluorination, 14 and cross-coupling. 15- 17 A dditionally, the w ell-studied area of oxidation chem istry w ith iron com plexes has m ade great strides in m echanistic understanding, substrate scope, chem o-, regio-, and enantioselectivity, and pertinence to industrial applications. 18- 22 The new ligand investigated herein, [ 2 ]H 2 ([ 2 ]H 2 ) (2,6- N C 5 H 3 (2-(2,4,6-M e 3 C 6 H 2 )-N H C 6 H 4 ) 2 ), possesses tw o fea- tures w hich m ay engender unique properties upon com plex- ation w ith iron.iron....
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This note was uploaded on 02/22/2011 for the course CH 3a taught by Professor Asdf during the Winter '11 term at Caltech.
- Winter '11