Construction and Function of One-dimensional Organometallic Composites Consisting of π-Conjugated Molecule and Metal Chain

聚乙炔、聚亚苯基等π共轭分子作为有机功能材料受到了广泛的关注，而一维多金属线作为无机功能材料和催化剂也受到了广泛的关注。本课题的目标是通过有机和无机共轭体系的配位键结合来构建线性有机金属复合物，并研究其在功能复合物中的催化和电性能。我们首次合成了含六个乙腈配体的Pd-Pd键合配合物，该配合物适合于被配位能力较弱的不饱和烃配体取代。该配合物与1，6-二苯基己三烯反应，得到了两个己三烯配体与Pd-Pd原子配位的夹心配合物。通过X射线晶体学测定了新的夹心配合物的结构。给定多烯的反应在n-3当量Pd（0）存在下，将Pd（3）-四烯（n = 1）与乙腈Pd-Pd配合物反应，得到了由（Pd）n-1链和两个多烯配体组成的线性夹心配合物，并发现室温光照射（>510 nm）可诱导该夹心配合物的内消旋异构体和外消旋异构体之间的相互转化，而在室温下黑暗中不发生这种相互转化。用还原剂或氧化剂处理Pd 3夹心层，没有导致类似的异构化。

Great attention has been paid to π-conjugated molecules such as polyacetylenes and polyphenylenes as functional organic materials, while one-dimensional polymetal wires also attract attention as inorganic functional materials and catalysts. The objective of the current project is to construct linear organometallic composites by combining these organic and inorganic conjugate systems via coordination bond, and to examine their catalytic and electric properties for application to the functional composites.We first attained the synthesis of Pd-Pd bonded complex containing six acetonitrile ligands, which suit for substitution by rather weakly coordinating unsaturated hydrocarbon ligands. This Pd-Pd complex reacted with 1,6-diphenylhexatriene to give sandwich complex in which two hexatriene ligands coordinate with the Pd-Pd moiety. The structure of the new sandwich complex was determined by X-ray crystallography. The reaction of a given polyene (double bond number = n) with acetonitrile Pd-Pd complex in the presence of n-3 equivalent Pd(0) afforded linear sandwich complex composed of (Pd)n-1 chain and two polyene ligands.We also found that photo-irradiation (>510 nm) at room temperature of Pd3-tetraene sandwich complex induces interconversion between meso and racemi isomers of this sandwich complex, while no such interconversion takes place under dark at room temperature. Treatment of the Pd3 sandwich with reducing or oxidizing reagent led to no similar isomerization.