二氧化硅负载的聚-γ-氨丙基硅氧烷—金属络合物的结构及催化羰基化作用的研究

Study of Structure and Catalytic Carbonylation of Silica- Supported Poly-γ-Aminopropylsiloxane-Metal Complexes

合成了二氧化硅负载的聚-γ-氨丙基硅氧烷(SiO_2>Si—NH_2)的单金属和双金属络合物(SiO_2>Si-NH_2—M和SiO_2>Si—NH_2—Co—M’,M=Co,Cu或Ru,M’=Cu或Ru),用XPS、IR和TEM研究了这些络合物的结构.证明,在这些金属络合物中,氮与金属间以配位键结合,金属的配位形式不是单一的.这与一般的小分子金属络合物不同.通过研究SiO_2>Si—NH_2—Co—Cu对苯胺氧化乙氧羰基化生成N-苯基氨基甲酸乙酯反应以及SiO_2>Si—NH_2—Co—Ru对环己烯醛化生成环己基甲醛和环己基甲醇反应的催化作用得知,双金属络合物中两种金属间存在相互作用.

In the previous papers[1,2], the catalytic properties of silica - supported poly -γ- aminopropyl -siloxane-metal complexes for hydrogenation and carboxylation have been studied. But the structure of the complexes has not been investigated in detail. Recently, the structure of silica-supported poly-γ-aminopropysil oxane-monometal and bimetal complexes (SiO2>Si- NH2- M and SiO2>Si - NH2 -Co - M' , M = Co, Cu or Ru, M'=Cu or Ru)have been investigated with XPS, IR and TEM, and the catalytic behaviors of the complexes for hydroformylation of cyclohexene and oxidative ethoxycarbonylation of aniline have also been studied.In XPS, the binding energy of nitrogen in the complexes is higher than that in SiO2>Si -NH2, and the binding energies of metals and chlorine in the complexex are lower than those in the corresponding metal chlorides.The XPS peaks of metals in the complexes become broader than those in the metal chlorides. All these results confirmed that coordination bonds were formed between metals and the nitrogen in the complexes, and the coordination pattern was not single.In IR, the absorption bands of - NH2at 1570 cm-1 in SiO2>Si -NH2shifted to 1600-1620 cm-1 when the complexes were formed. We also observed the bands of N-Ru in far-infrared region for SiO2>Si -NH2-Ru and SiO2>Si -NH2-Co-Ru.TEM results indicated that no zero-valent metals were precipitated to the support.It has been found that the catalytic property of SiO2>Si -NH2 -Co-M' is different from SiO2 >Si -NH2 -M' or SiO2>Si -NH2 -Co by studying the influence of Co/M' ratio on the catalytic carbonylation property of SiO2> Si - NH2 - Co - M'. It was confirmed that there was synergistic action between different metals in the bimetallic complex.All results indicated that the structure of the complexes can be expressed by the formula (2) and (3).