High-Spin Building Blocks for Molecule Based Magnets with Ferromagnetic Interaction based on Double Exchange

为了构建一类新的基于分子的磁体，需要允许它们的顺磁中心之间的强铁磁相互作用的分子构建块（分子）。这个研究项目是基于双交换的概念，这是已知的传播强铁磁相互作用的混合价系统。混合价面八面体中电子离域的概念将从双核和三核（零维）配合物扩展到一维链状化合物。选择新的配体2，6-二羟甲基苯酚及其硫衍生物合成了两个金属离子以共面方式桥联的双核分子配体。这种新型的金属配体能够通过O3-或S3-配体组在两侧与其他金属离子配位以构建一维链。在混合价体系中，期望基态，电子在整个链上离域。这种离域应导致强铁磁相互作用的双交换机制伴随着一维电导率。磁和电特性的切换行为的可能性由金属到金属的电荷转移吸收给出，其对应于激发到没有铁磁相互作用和导电性的局部电子状态。

In order to build a new class of molecular based magnets, molecular building blocks (synthons) which allow for strong ferromagnetic interactions between their paramagnetic centers are needed. This research project is based on the concept of double exchange which is known to propagate strong ferromagnetic interactions in mixed valence systems. The concept of electron delocalization in mixed valence face-sharing octahedra will be extended from bi- and trinuclear (zero-dimensional) complexes to one-dimensional chain compounds. The new ligand motive 2,6-dihydroxymethylphenol and the sulfur derivatives is chosen in order to synthesize binuclear molecular synthons with two metal ions bridged in a face sharing fashion. This novel metallo-ligand is capable to coordinate on both sides to other metal ions by a O3- or S3-ligand set to build one-dimensional chains. In the mixed valence systems, a ground state is expected with electrons delocalized over the whole chain. This delocalization should lead to a strong ferromagnetic interaction by a double exchange mechanism accompanied by one-dimensional electric conductivity. The possibility of a switching behaviour of the magnetic and electrical properties is given by the metal-to-metal charge transfer absorption which corresponds to an excitation into a localized electronic state without ferromagnetic interactions and electrical conductivity.