McKenzie Iain
Centre for Molecular and Materials Science, TRIUMF, 4004 Wesbrook Mall, Vancouver, B.C., Canada.
Phys Chem Chem Phys. 2014 Jun 14;16(22):10600-6. doi: 10.1039/c4cp00618f.
Radicals formed by the reaction of muonium (Mu), a light isotope of hydrogen, with ferrocene and ferrocene-d10 have been studied with the avoided level crossing muon spin resonance (ALC-μSR) and longitudinal field muon spin relaxation (LF-μSR) techniques between 10 and 100 K. A single type of radical was observed in each compound and the muon hyperfine coupling constants (hfcc) and the muon spin relaxation rates were measured as a function of temperature. A previous report concerning the observation of Mu adducts of ferrocene (U. A. Jayasooriya et al. Chem. - Eur. J., 2007, 13, 2266-2276) appears to be incorrect. DFT calculations were performed to aid in the assignment of the ALC-μSR spectra. A tentative assignment is that the observed radicals were formed by Mu addition to the exterior of the cyclopentadienyl rings and that the structures are distorted due to interactions with neighbouring molecules. The temperature dependence of the muon hfcc can be explained assuming the population of two levels with different muon hfccs separated by 1.4 ± 0.1 kJ mol(-1). The temperature dependence of the width and amplitude of the Δ1 resonance and the muon spin relaxation rate suggests that the electron spin relaxation rate increase with temperature, but the relaxation mechanism is unknown.
利用避免能级交叉μ子自旋共振（ALC-μSR）和纵向场μ子自旋弛豫（LF-μSR）技术，在10至100 K的温度范围内研究了氢的轻同位素μ子（Mu）与二茂铁和二茂铁-d10反应形成的自由基。在每种化合物中均观察到单一类型的自由基，并测量了μ子超精细耦合常数（hfcc）和μ子自旋弛豫率随温度的变化。先前一篇关于二茂铁的Mu加合物的观察报告（U. A. Jayasooriya等人，《化学 - 欧洲杂志》，2007年，13卷，2266 - 2276页）似乎有误。进行了密度泛函理论（DFT）计算以辅助ALC-μSR光谱的归属。初步归属为观察到的自由基是由Mu加成到环戊二烯基环的外部形成的，并且其结构由于与相邻分子的相互作用而发生扭曲。假设存在两个具有不同μ子hfcc的能级，其间隔为1.4±0.1 kJ mol⁻¹，这样可以解释μ子hfcc的温度依赖性。Δ1共振的宽度和幅度以及μ子自旋弛豫率的温度依赖性表明电子自旋弛豫率随温度增加，但弛豫机制尚不清楚。
