Haim Lorraine, Robert François, Peres Laurent, Lecante Pierre, Philippot Karine, Poteau Romuald, Respaud Marc, Amiens Catherine
LCC (Laboratoire de Chimie de Coordination) BP44099, 205 route de Narbonne F-31077 Toulouse Cedex 4 France
Université de Toulouse, UPS, INPT F-31077 Toulouse Cedex 4 France.
Nanoscale Adv. 2021 Jun 29;3(15):4471-4481. doi: 10.1039/d1na00258a. eCollection 2021 Jul 27.
To shed light on the factors governing the stability and surface properties of iron nanoparticles, a series of iron nanoparticles has been produced by hydrogenation of two different iron amido complexes: the bis[bis(trimethylsilyl)amido] Fe(ii), [Fe(N(SiMe))], and the bis(diphenylamido) Fe(ii), [Fe(NPh)]. Nanostructured materials of bcc structure, or nanoparticles displaying average sizes below 3 nm and a polytetrahedral structure, have been obtained. Depending on the synthesis conditions, the magnetization of the nanoparticles was either significantly lower than that of bulk iron, or much higher as for clusters elaborated under high vacuum conditions. Unexpectedly, hydrogenation of aromatic groups of the ligands of the [Fe(NPh)] precursor has been observed in some cases. Confrontation of the experimental results with DFT calculations made on polytetrahedral Fe model clusters bearing hydrides, amido and/or amine ligands at their surface, has shown that amido ligands can play a key role in the stabilisation of the nanoparticles in solution while the hydride surface coverage governs their surface magnetic properties. This study indicates that magnetic measurements give valuable indicators of the surface properties of iron nanoparticles in this size range, and beyond, of their potential reactivity.
为了阐明控制铁纳米颗粒稳定性和表面性质的因素，通过氢化两种不同的铁酰胺配合物制备了一系列铁纳米颗粒：双[双（三甲基硅基）酰胺]铁（II），[Fe(N(SiMe))]，和双（二苯基酰胺）铁（II），[Fe(NPh)]。已获得体心立方结构的纳米结构材料，或平均尺寸低于3nm且具有多面体结构的纳米颗粒。根据合成条件，纳米颗粒的磁化强度要么显著低于块状铁，要么在高真空条件下制备的团簇中则要高得多。出乎意料的是，在某些情况下观察到了[Fe(NPh)]前体配体的芳基氢化。将实验结果与对表面带有氢化物、酰胺和/或胺配体的多面体铁模型团簇进行的密度泛函理论计算进行对比，结果表明酰胺配体在溶液中纳米颗粒的稳定化中可以发挥关键作用，而氢化物表面覆盖率决定了它们的表面磁性质。这项研究表明，磁性测量为该尺寸范围内及更大尺寸的铁纳米颗粒的表面性质及其潜在反应性提供了有价值的指标。
