Innovative Sulfur-Nitrogen Ligands for Promising Ln3+ Single Molecule Magnets

该提议的主要目标是合成和表征含硫氮配体的稀土有机金属SMM络合物，同时进行根深蒂固的X射线和中子衍射电荷和自旋密度研究。我们将合成、表征、结构和磁性研究含硫中心聚酰亚胺配体S(NR)32-、S(NR)42-、RS(NR)2-、RS(NR)3-、(R2C)S(NR)22-和(R2C)S(NR)32-的f元素配合物。配体组合将由Ph_2PCH_2S(NR)_2-、Ph_2PCH_2S(NR)_3-和(NR)_2SCH_2Py-(Py=2-吡啶)组成。易适应的N-S-N键角与软硫原子一起保证了大的磁各向异性和缓慢的磁弛豫，这是好的SMM所不可避免的。除了这些单阴离子和双阴离子配体外，我们还将使用我们的自由基单阴离子S(NR)3·-配体来评估有多少自旋密度是以金属和配体为中心的，以及这对磁性的影响是什么。当然，这在SMM的设计中应该很重要。目前，从EPR谱我们知道自由基是以N为中心的，这肯定会影响镧系元素原子的自旋密度。作为金属源，我们将使用稀土三卤化物LnHal3，Ln=Gd，Tb，Dy，Ho，Er，三乙酰丙酮酸盐Ln(Acac)3和三酰胺Ln{N(SiMe3)2}3。关于电子局域的结构测定和研究将远远超出经典的单晶结构分析。我们将从高分辨率的衍射数据中研究它们，并将沿着多极模型模拟它们的结构。我们将沿着分子中原子的量子理论来分析它们的性质。除了电子密度的测定外，我们还计划通过实验测定自旋密度。因此，我们需要使用中子衍射，既可以精确地确定原子核的位置，也可以确定磁矩。这将有望从极化中子衍射实验中得到便利。所确定的电荷密度使得能够直接推导出具有物理意义的原子和键的性质。进一步的化学和物理性质，如反应表面和静电势是可以获得的，这对于设计用于SMM的积木至关重要。总而言之，我们已经掌握了进一步开发这一最富有成果的领域的配体和方法。

The main objective of the proposal is the synthesis and characterisation of lanthanide organometallic SMM complexes comprising sulfur-nitrogen ligands together with a deeply-rooted X-ray and neutron diffraction based charge and spin density investigation. We will synthesize, characterize, structurally and magnetically investigate f-element complexes containing the sulfur-centred polyimido ligands S(NR)32–, S(NR)42–, RS(NR)2–, RS(NR)3–, (R2C)S(NR)22–, and (R2C)S(NR)32–. The ligand portfolio will be completed by the scorpionates Ph2PCH2S(NR)2–, Ph2PCH2S(NR)3– and (NR)2SCH2Py–, (Py = 2-pyridyl). Easy adaptable N-S-N bond angels together with the soft sulfur atom promise large magnetic anisotropy and slow magnetic relaxation, inevitable for good SMMs. In addition to these mono- and dianionic ligands we will employ our radical monoanionic S(NR)3•– ligand to evaluate how much of the spin density is metal- and ligand-centred and what the effect is on the magnetic properties. This of course should matter in the design of SMMs. Currently from the EPR spectra we know the radical to be N-centred and certainly will affect the spin density at the lanthanide atom. As metal sources we will use the lanthanide trihalides LnHal3, Ln = Gd, Tb, Dy, Ho, Er, triacetylacetonates Ln(acac)3 and triamides Ln{N(SiMe3)2}3. The structural determinations and investigations concerning the localisation of electrons in the proposed compounds will go far beyond the classical single crystal structure analysis. We will investigate them from high-resolution diffraction data and their structures will be modelled along the multipole model. Their properties will be analysed along the quantum theory of atoms in molecules. In addition to the electron density determination we plan to experimentally determine the spin density. Hence we need to employ neutron diffraction, either to determine the nuclei position precisely and to determine the magnetic moment. This will hopefully be facilitated from polarised neutron diffraction experiments. The determined charge density enables the direct deduction of physically meaningful atomic and bond properties. Further chemical and physical properties like the reactive surface and the electrostatic potential are accessible, crucial for the design of building blocks to give SMMs. To conclude we got the ligands and the methods in hand to further develop that most fruitful field.