Synthesis and characterization of double metal cyanides and their applications as polymerization catalysts /
Metallocyanides have long been studied for their ability to act as ligands to other metals. This property gives rise to the diverse applications of the resulting bridged complexes. Among these applications are the ability to act as geometric building blocks, and as catalysts for the coupling of ep...
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| Format: | Thesis Book |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
2002.
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| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=726477151&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | Metallocyanides have long been studied for their ability to act as ligands to other metals. This property gives rise to the diverse applications of the resulting bridged complexes. Among these applications are the ability to act as geometric building blocks, and as catalysts for the coupling of epoxides and CO₂. Unfortunately, double metal cyanides have a propensity towards aggregation, which hinders the characterization of the resulting complexes. It is the purpose of this work to synthesize soluble model complexes of poorly characterized double metal cyanide catalysts from the patent literature, and to further the development of their use in molecular architecture. To this end, a number of soluble double metal cyanide complexes with the core unit comprised of CpFe(CN)₂(L) (L= CO or PR₃) have been synthesized. This cyanometalate is then bound to Cu(I) or Zn(II) through the cyanide nitrogen. Thus, the products of these reactions take on rhombohedral geometries with the metal centers bridged by cyanide ligands. In cases where the products of the reactions were aggregates, protecting ligands were used to block their formation. Traditionally chelating phosphines have also been used to create a bridged diiron metalocyanide source. This species is a new type of chelate, which has been used to form basket shaped double metal cyanide complexes. The chelate nature of the iron dicyanide serves to further strengthen the already robust metallocyclic core. Furthermore, the length of the bridge may be tailored to control the planarity of the rhombohedral unit. The utility of these complexes as catalysts has also been explored. It was found that they do indeed couple epoxides and CO₂ to form polycarbonates. A diminished activity is seen in these model catalysts, as well as an increase in the amount of cyclic carbonate produced. Despite their deficiencies, these model catalysts have paved the way for a better understanding of the industrial heterogeneous systems. |
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| Item Description: | Vita. "Major Subject: Chemistry". |
| Physical Description: | xiii, 130 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilm Inc. |
| Bibliography: | Includes bibliographical references (leaves 123-126). |