862169-55-9Relevant academic research and scientific papers
Synthesis of bis(imino)pyridine iron di- And monoalkyl complexes: Stability differences between FeCH2SiMe3 and FeCH 2CMe3 derivatives
Fernandez, Ignacio,Trovitch, Ryan J.,Lobkovsky, Emil,Chirik, Paul J.
, p. 109 - 118 (2008/10/09)
The scope of aryl-substituted bis(imino)pyridine iron dihalide alkylation and arylation reactions has been explored with LiCH2SiMe3, LiCH2CMe3, and LiPh. Dialkylation was only observed when the 2,6-diisopropylaryl-substituted iron complex was treated with 2 equiv of LiCH2SiMe3. In all other cases, reductive alkylation to form four-coordinate bis(imino)pyridine iron monoalkyl complexes occurred. One of these products, (EtPDI)FeCH2CMe3 [ EtPDI = 2,6-(2,6-Et2C6H3N=CMe) 2C6H3N)], has been crystallographically characterized and shown to exhibit a distorted square planar geometry arising from the steric disposition of the alkyl group. Five-coordinate bis(imino)pyridine iron aryl"ate" complexes bearing weakly activated dinitrogen ligands were isolated from treatment of the corresponding dihalide with 3 equiv of aryllithium. The tolyl derivative was characterized by X-ray diffraction, and a distorted square pyramidal structure was established where the dinitrogen ligand completes the idealized basal plane. Ligand substitution reactions where the terdentate bis(imino)pyridine is used to displace pyridine from Py2Fe(R)X (R = CH2SiMe3, CH 2CMe3; X = Cl, CH2SiMe3, CH 2CMe3) further demonstrated the relative stability of five-coordinate FeCH2SiMe3 versus FeCH2CMe 3 complexes. For the neopentyl compounds, ejection of a neopentyl radical or alkylation of the p-pyridine position of the chelate was observed.
Metal versus ligand alkylation in the reactivity of the (bis-iminopyridinato)Fe catalyst
Scott, Jennifer,Gambarotta, Sandro,Korobkov, Ilia,Budzelaar, Peter H. M.
, p. 13019 - 13029 (2007/10/03)
The alkylation of the Brookhart-Gibson {2,6-[2,6-(i-Pr)2PhN= C(CH3)]2(C5H3N)} FeCl2 precatalyst with 2 equiv of LiCH2Si(CH3)3 led to the isolation of several catalytically very active products depending on the reaction conditions. The expected dialkylated species {2,6-[2,6-(i-Pr) 2PhN=C(CH3)]2}(C5H 3N)Fe(CH2-SiMe3)2 (2) was indeed the major component of the reaction mixture. However, other species in which alkylation occurred at the pyridine ring ortho position, {2,6-[2,6-(i-Pr) 2PhN=C(CH3)]2-2-CH2SiMe 3}-(C5H3N)Fe(CH2SiMe3) (1), and at the imine C atom, {2-[2,6-(i-Pr)2PhN=C(CH 3)]-6-[2,6-(i-Pr)2PhNC(CH3)-(CH2 SiMe3)](C5H3N)}Fe(CH2SiMe 3) (3), have also been isolated and fully characterized. In addition, deprotonation of the methyl-imino functions and formation of a new divalent Fe catalyst {[2,6-[2,6-(i-Pr)2PhN-C=(CH2)]2(C 5H3N)}Fe(μ-Cl)Li(THF)3 (4) also occurred depending on the reaction conditions. In turn, the formation of 4 might trigger the reductive coupling of two units through the methyl-carbon wings. This process resulted in the one-electron reduction of the metal center, affording a dinuclear Fe(I) alkyl catalyst {[{[2,6-(i-Pr)2C6H 5]N=C(CH3)}(C5H3N){[2,6-(i-Pr) 2C6H5]N=CCH2}Fe(CH 2SiMe3)]}2 (5). Different from other metal derivatives, complex 5 could not be prepared from the monodeprotonated version of the ligand. Its reaction with a mixture of FeCl2 and RLi afforded instead [{2,6-[2,6-(i-Pr)2PhN-C=(CH2)]2(C 5H3N)}FeCH2Si(CH3) 3]-[Li(THF)4] (6) which is also catalytically active. All of these high-spin species have been shown to have high catalytic activity for olefin polymerization, producing polymers of two distinct natures, depending on the formal oxidation state of the metal center.
Square planar bis(imino)pyridine iron halide and alkyl complexes
Bouwkamp, Marco W.,Bart, Suzanne C.,Hawrelak, Eric J.,Trovitch, Ryan J.,Lobkovsky, Emil,Chirik, Paul J.
, p. 3406 - 3408 (2007/10/03)
Square planar iron methyl complexes containing bis(imino)pyridine (PDI) ligands have been prepared by reductive alkylation of the corresponding ferrous dichloride; dialkylation is observed upon treatment with a larger alkyl lithium. The Royal Society of Chemistry 2005.
