respectively, confirming ligand-based oxidation. Electron paramagnetic resonance (EPR) spectroscopy exhibited a typical high spin FeIII (S = 5/2) signal for the neutral complexes in perpendicular mode. Upon oxidation, a signal at g ≈ 9 was observed in parallel mode, suggesting the formation of a spin integer system arising from magnetic interactions between the high spin FeIII center and the phenoxyl radical
的Fe III对称(2络合物的小号,2'小号) - [ Ñ,Ñ ' -双(1-(2-羟基-3,5-二-叔-butylphenylmethyl))] - 2,2'-联吡咯烷(H 2 L 1)和不对称的(2 S,2 'S)-[ N,N '-(1-(2-羟基-3,5-二叔丁基苯基甲基))-2-(吡啶甲基)]-2制备了带有联吡咯烷骨架的2,-联吡咯烷(HL 2)配体,并研究了中性和单电子氧化物种的电子结构。FeL的循环伏安图(CV)1 Cl和FeL 2 Cl 2显示出预期的氧化还原波,对应于酚盐部分氧化成苯氧基自由基,这是通过用1当量的合适化学氧化剂处理络合物来实现的。中性配合物从干净转变为氧化态的过程通过UV-vis-NIR光谱仪进行监测,其中出现了苯氧基自由基的强烈π-π*跃迁特征( [FeL 1 Cl] +•:25 500 cm –1( 9000 M –1 cm –1); [ FeL 2 Cl
Dioxidomolybdenum(VI) Complexes Containing Ligands with the Bipyrrolidine Backbone as Efficient Catalysts for Olefin Epoxidation
作者:Ramasamy Mayilmurugan、Pedro Traar、Jörg A. Schachner、Manuel Volpe、Nadia C. Mösch‐Zanetti
DOI:10.1002/ejic.201300258
日期:2013.7.12
around the molybdenum(VI) center with a cis- configuration. The Mo-O-oxo bond lengths are almost equal and vary only between 1.701 and 1.7091 angstrom. Complexes 1 and 2 were found to be efficient and selective catalysts for various olefinepoxidation reactions. Catalyst loadings of 0.5 mol-%, the use of 2 equiv. of oxidant (tert-butyl hydroperoxide), as well as unchanged catalyst performance over three
Salan ligands assembled around chiral bipyrrolidine: predetermination of chirality around octahedral Ti and Zr centres
作者:Ekaterina Sergeeva、Jacob Kopilov、Israel Goldberg、Moshe Kol
DOI:10.1039/b823176a
日期:——
The first synthesis of Salan ligands assembled around the chiral 2,2'-bipyrrolidine backbone is described; as chelation to a metal can only occur via specific faces of the two pyrrolidine nitrogens, these ligands lead to predetermined chirality at metal centres of octahedral titanium and zirconium complexes.