Synthesis and characterisation of a Ru~(II)([14]aneS_4) complex immobilised inMCM-41-type mesoporous silica

摘要

Ruthenium(u) complexes containing the macrocycle 1,4,8,1 l-tetrathiacyclotetradecane ([l4JaneS4) and nitrogen-coordinated nitrile ligands were prepared using cis-tRu(DMSQ)4C121 as the starting material. The first synthetic step consisted of introduction of the thioether ligand to give [Ru([l4IaneS4)(DMSO)ClICI. Substitution of the DM50 ligand by the nitrile ligands NCCH, or NC(CH2),Si(OEt)3 (L) gave the complexes [Ru([l4IaneS4)(L)CI]X (X = Cl, PF6). Introduction of the triethoxysilyl ligand allowed the [Ru([l4IaneS4)ClI~ fragment to be tethered to the surface of the ordered mesoporous silica MCM-41 by pore volume impregnation of a solution of the complex in dichloromethane. A high metal loading was achieved (0.56 mmol g~(-1)). Powder XRD and N2 adsorption studies of the derivatised material indicated that the textural properties of the support were preserved during the grafting experiment and that the channels remained accessible, despite a large reduction in both surface area and pore volume (ca. 50%). IR, UV/VIS, photoluminescence and MAS NMR spectroscopy (~(13)C, ~(29)Si) confirmed that the structural integrity of the Ruil complex was retained during immobilisation, except for loss of ethoxide groups due to the reaction with pendant silanols on the silica surface.