Part I. Synthesis and thermolysis of cyclopentadienyl and pentamethylcyclopentadienyl molybdenum dioxo alkoxides. Part II. Structural characterization of polysilicate intermediates formed during sol-gel polymerization

Chemistry, Analytical;Chemistry, Inorganic;Engineering, Chemical

Rosenberg, Frank Stewart

关键词: Chemistry, Analytical;    Chemistry, Inorganic;    Engineering, Chemical;   

Others  :  https://www.ideals.illinois.edu/bitstream/handle/2142/18981/9026307.pdf?sequence=2&isAllowed=y

美国|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

Part I. The molybdenum(VI) dioxo alkoxides ($\eta\sp5$-$C\sb5$H$\sb5$)MoO$\sb2$(OR) (R=CH$\sb2$CH$\sb3$, CH(CH$\sb3)\sb2$) and ($\eta\sp5$-C$\sb5$(CH$\sb3)\sb5$) MoO$\sb2$(OR) (R=CH$\sb3$, CH$\sb2$CH$\sb3$, CH(CH$\sb3)\sb2$) have been prepared and characterized. Single crystal X-ray diffraction studies showed that CpMoO$\sb2$(OCH$\sb2$CH$\sb3$) and Cp$\sp{*}$MoO$\sb2$(OCH$\sb2$CH$\sb3$) adopt the expected piano stool geometry. Oxygen-17 NMR chemical shifts of the terminal oxygens showed that Cp$\sp{*}$ is a better electron donor to the metal center than Cp. Oxygen-17 NMR also showed that for a series of compounds, CpMoO$\sb2$(OR) (R=Me, Et, i-Pr and t-Bu), electron donation increased in the order methoxide $Part II. The principle mono- through hexasilicate structural isomers formed by hydrolysis of methanolic tetramethylorthosilicate in the presence of HCl have been structurally assigned and quantitatively determined. Complex silica sol-gel mixtures were separated into several simpler samples which were characterized by gas chromatography and mass spectrometry (Ramamurthi, S. D. Ph.D. Thesis, University of Illinois, 1988). The contents of each sample were structurally characterized and quantified by $\rm \sp{29}Si\{\sp1H\}$ NMR techniques (1-pulse, 1D-INADEQUATE and 2D-INADEQUATE). By comparing the NMR data with the gas chromatographic data, structural assignments were made and response factors were calculated for each of the components separated by gas chromatography.