Anorganisch-Chemisches Institut, Universität Heidelberg, INF 270, D-69120 Heidelberg, Germany.
Inorg Chem. 2012 Mar 5;51(5):2841-51. doi: 10.1021/ic2019296. Epub 2012 Feb 14.
The reactivity of copper complexes of three different second-generation bispidine-based ligands (bispidine = 3,7-diazabicyclo[3.3.1]nonane; mono- and bis-tetradentate; exclusively tertiary amine donors) with dioxygen [(reversible) binding of dioxygen by copper(I)] is reported. The UV-vis, electrospray ionization mass spectrometry, electron paramagnetic resonance, and vibrational spectra (resonance Raman) of the dioxygen adducts indicate that, depending on the ligand and reaction conditions, several different species (mono- and dinuclear, superoxo, peroxo, and hydroperoxo), partially in equilibrium with each other, are formed. Minor changes in the ligand structure and/or experimental conditions (solvent, temperature, relative concentrations) allow switching between the different forms. With one of the ligands, an end-on peroxodicopper(II) complex and a mononuclear hydroperoxocopper(II) complex could be characterized. With another ligand, reversible dioxygen binding was observed, leading to a metastable superoxocopper(II) complex. The amount of dioxygen involved in the reversible binding to Cu(I) was determined quantitatively. The mechanism of dioxygen binding as well as the preference of each of the three ligands for a particular dioxygen adduct is discussed on the basis of a computational (density functional theory) analysis.
报道了三种不同的第二代双齿吡啶基配体（双吡啶= 3,7-二氮杂双环[3.3.1]壬烷；单核和双四齿配体；仅为叔胺供体）的铜配合物与氧气（铜（I）与氧气的可逆结合）的反应性。氧气加合物的紫外可见光谱、电喷雾质谱、电子顺磁共振和振动光谱（共振拉曼）表明，根据配体和反应条件，形成了几种不同的物种（单核和双核、超氧、过氧和过氢过氧），它们部分处于平衡状态相互之间。配体结构和/或实验条件（溶剂、温度、相对浓度）的微小变化允许在不同形式之间切换。对于其中一种配体，可以对端氧过氧二铜（II）配合物和单核过氢过氧铜（II）配合物进行表征。对于另一种配体，观察到氧气的可逆结合，导致亚稳的超氧合铜（II）配合物的形成。定量确定了与 Cu（I）可逆结合的氧气量。基于计算（密度泛函理论）分析，讨论了氧气结合的机制以及三种配体中每一种对特定氧气加合物的偏好。
