Ruthenium complexes with naphthyridine ligands. Synthesis, characterization and catalytic activity in oxidation reactions †
作者:Alexandra E. M. Boelrijk、Thomas X. Neenan、Jan Reedijk
DOI:10.1039/a702983g
日期:——
New ruthenium complexes with 1,8-naphthyridine (napy) or derivatives thereof as ligands have been prepared and characterized. Three groups of complexes were obtained. The first consists of three dinuclear ruthenium complexes with two ligands (1,8-naphthyridine and pyridopyrazine) co-ordinated to two ruthenium ions in a bridging fashion. The second consists of two ruthenium dinuclear complexes having one ligand (2,7-dimethoxy- or 2,7-dichloro-1,8-naphthyridine, abbreviated to dmnapy and dcnapy respectively) co-ordinated to two ruthenium atoms. Proton NMR spectra for both complexes in aqueous solution and in acetonitrile revealed the conversion of a symmetrical form, suggesting dinucleating behaviour of the ligand, into an asymmetrical form, suggesting mononucleating behaviour of the ligand. The third group consists of a mono- and a di-nuclear complex with the ligand 2,7-di(phenylazo)-1,8-naphthyridine. The catalytic activity of the novel naphthyridine complexes in oxidation reactions has been studied. The catalytic oxidation of alcohols and the epoxidation of trans-stilbene were examined and the different reaction rates and selectivities are discussed in a comparative way. The active high-valent species resulting from the [Ru2(napy)2(H2O)4Cl(OH)]4+ complex is discussed in more detail.
以 1,8-萘啶(napy)或其衍生物为配体的新型钌配合物已经制备完成,并对其进行了表征。共获得三组配合物。第一组由三个双核钌配合物组成,其中两个配体(1,8-萘啶和吡啶并嗪)以桥接方式与两个钌离子配位。第二种由两个钌二核配合物组成,其中一个配体(2,7-二甲氧基-或 2,7-二氯-1,8-萘啶,分别简称为 dmnapy 和 dcnapy)与两个钌原子配位。这两种配合物在水溶液和乙腈中的质子核磁共振光谱显示,配体由对称形式转化为不对称形式,表明配体具有双核作用。第三组由配体 2,7-二(苯基偶氮)-1,8-萘啶的单核和双核配合物组成。研究了新型萘啶配合物在氧化反应中的催化活性。研究考察了醇的催化氧化反应和反式二苯乙烯的环氧化反应,并对不同的反应速率和选择性进行了比较讨论。更详细地讨论了[Ru2(napy)2(H2O)4Cl(OH)]4+ 复合物产生的活性高价物种。