An Iron(II) Complex of a Diamine-Bridged Bis-N-Heterocyclic Carbene

Abstract

A diamine-bridged bis-N-heterocyclic carbene ligand was synthesized as imidazolium salts with chloride or triflate counteranions. Deprotonation of the chloride salt by an iron bis-amide complex or addition of the free diamine-biscarbene ligand to FeCl 2 led to the formation of an Fe(II) dichloride complex having a diamine-bis-carbene ligand, in which the iron atom is in a highly distorted octahedral geometry with weak Fe-N interactions. This iron complex was found to catalyze the hydrosilylation of acetophenone.

Catalytic Activity of Iron N-Heterocyclic Carbene Complexes

“…Iron will remain a metal of choice for the replacement of all the heavy metal ions currently being used for the application of catalytic processes for the obvious reason Table 3. Other examples of reduction reactions [53][54][55][56][57][58][59][60]. Catalytic Activity of Iron N-Heterocyclic Carbene Complexes DOI: http://dx.doi.org/10.5772/intechopen.90640 of it being economical, very high natural abundance, environmentally benign and more importantly biologically compatible.…”

Iron N‐Heterocyclic Carbenes in Reduction Reactions

“…Apart from the intensively explored half‐sandwich Fe(II)‐NHC complexes, the only other well‐defined Fe(II)‐NHC complexes catalysing the hydrosilylation of ketones are the square‐planar trans ‐(IMes) 2 FeMe 2 ( 11 ) and the bis‐NHC−Fe complex 15 (Scheme ) described by Glorius ,. Hydrosilylation of 2'‐acetonaphthone in good yield (91–96 %) was afforded by using 1.2 mol % of 11 and 1.1 equivalent of silanes (Ph 2 SiH 2 , (EtO) 3 SiH) at room temperature (Scheme ) .…”

“…Hydrosilylation of 2'‐acetonaphthone in good yield (91–96 %) was afforded by using 1.2 mol % of 11 and 1.1 equivalent of silanes (Ph 2 SiH 2 , (EtO) 3 SiH) at room temperature (Scheme ) . Complex 15 displayed comparable catalytic activity in the reduction of acetophenone although higher temperature (60 °C) was needed to reach high yields …”

Coupling of an N‐Heterocyclic Carbene on Iron with Alkynes to Form η5‐Cyclopentadienyl‐Diimine Ligands

“…[7] Treatment of complex 1 [7a] bearing a cyclometalated NHC ligand with two equivalents of phenylacetylene at 60 8C resulted in the formation of a red solution after three days, from which crystals of ferrocenyl-diimine complex 2 a, having two phenyl groups at the 2-and 4-positions of the cyclopentadienyl ring, were isolated in 79 % yield (Scheme 1). [7] Treatment of complex 1 [7a] bearing a cyclometalated NHC ligand with two equivalents of phenylacetylene at 60 8C resulted in the formation of a red solution after three days, from which crystals of ferrocenyl-diimine complex 2 a, having two phenyl groups at the 2-and 4-positions of the cyclopentadienyl ring, were isolated in 79 % yield (Scheme 1).…”

“…The titled reaction was discovered during the course of our studies on the reactions of iron-NHC complexes. [7] Treatment of complex 1 [7a] bearing a cyclometalated NHC ligand with two equivalents of phenylacetylene at 60 8C resulted in the formation of a red solution after three days, from which crystals of ferrocenyl-diimine complex 2 a, having two phenyl groups at the 2-and 4-positions of the cyclopentadienyl ring, were isolated in 79 % yield (Scheme 1). Similarly, the reaction of 1 with diphenylacetylene gave an analogous complex 2 b, which was crystallized in 40 % yield.…”