Mononuclear diastereopure non-heme Fe(II) complexes of pentadentate ligands with pyrrolidinyl moieties: Structural studies, and alkene and sulfide oxidation

Abstract

Mononuclear iron(II) complexes of enantiopure Py(ProOH) 2 (2) and Py(ProPh 2 OH) 2 (3) ligands have been prepared with FeCl 2 and Fe(OTf) 2 AE 2MeCN. Both ligands coordinate to the metal in a pentadentate fashion. Next to the meridional N,N 0 ,N-coordination of the ligand, additional coordination of the oxygen atoms of both hydroxyl groups to the metal is found in complexes 4-7. Complex [FeCl(2)](Cl) (4) shows an octahedral geometry as determined by X-ray diffraction and is formed as a single diastereoisomer. The solution structures of complexes 4-7 were characterized by means of UV-Vis, IR, ESI-MS, conductivity and CD measurements. The catalytic potential of these complexes in the oxidation of alkenes and sulfides in the presence of H 2 O 2 is presented.

Stereogenic-at-Iron Catalysts with a Chiral Tripodal Pentadentate Ligand

“…Although a variety of different achiral pentadentate ligands and their corresponding iron complexes have been reported, , there are surprisingly few reports on the synthesis of well-defined chiral iron complexes from chiral pentadentate ligands − and only a handful of reports on asymmetric catalysis with chiral pentadentate iron complexes. One of the first examples was reported by the Ohno group.…”

“…Klein Gebbink reported iron­(II) complexes from a linear pentadentate ligand derived from a central bis-pyrrolidinyl pyridine pincer unit. The catalyst was employed in the oxidation of aryl methyl sulfides with H 2 O 2 to provide the corresponding sulfoxides with up to 27% ee . The most notable chiral pentadentate iron catalyst scaffold was reported by Kaizer .…”

Mono- and Dinuclear Iron Complexes of Bis(1-methylimidazol-2-yl)ketone (bik): Structure, Magnetic Properties, and Catalytic Oxidation Studies

“…On the other hand, synthetic mono- and dinuclear iron active site analogues serve as potential synthetic oxidation catalysts, and their properties have been widely explored also in this respect. Promising examples of mononuclear catalysts capable of alkane hydroxylation, olefin epoxidation, and cis -dihydroxylation have been reported. ,,,− Ligand systems that are widely used for the construction of both mono- and dinuclear iron complexes include the polydentate tris(2-pyridylmethyl)amine (tpa) and N , N ′-bis(2-pyridylmethyl)- N , N ′-dimethyl-1,2-ethylenediamine ligand family (bpmen) , and the N , N -bis(2-pyridylmethyl)- N -bis(2-pyridyl)methylamine (N4py), , 2-(2′,5′-diazapentyl)-5-bromopyrimidine-6-carboxylic acid N-[2,(4′-imidazolyl)ethyl]amide (Hpma), and tris((1-methylimidazol-2-yl)methyl)amine (tmima) ligands, among many others (Figure ). Efficient dinuclear iron oxidation catalysts were also reported, some of which with very simple bidentate ligands such as bipyridine (bipy) and phenanthroline (phen). ,, …”

Bio-inspired arenecis-dihydroxylation by a non-haem iron catalyst modeling the action of naphthalene dioxygenase

“…6 In the past few years, we and others have been successful in finding nonhaem iron catalysts that catalyse the cis-dihydroxylation of olefins. [7][8][9][10][11][12] However, the cis-dihydroxylation of aromatic double bonds by such catalysts has thus far not been reported. Here we report for the first time a non-haem iron complex that catalyses the cis-dihydroxylation of naphthalene and thus serves as a functional model for naphthalene 1,2-dioxygenase.…”