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Dissertation/Thesis Abstract

A solid state photolysis study of cis-diazidocyclamchromium(III)X complexes to examine the transformation that takes place as the particular azide evolves nitrogen gas to yield photooxidation products, cis-azidonitridocyclamchromium(V)X complexes
by Bria, Lauren Elizabeth, M.S., University of California, Davis, 2009, 122; 1468983
Abstract (Summary)

Numerous cis-diazido(1,4,8,11-tetraazacyclotetradecane)chromium(III)X complexes, (1,4,8,11-tetraazacyclotetradecane = cyclam), have been prepared; where X is BPh4-, PF6-, Cl-, BF4-, ClO3 -, N3-. Photolysis of the diazido complex causes the evolution of one mole of nitrogen gas, forming Cr ≡ N, the nitrido complex. When the [CrIII(N3)2(L)]X complex is photolyzed, (where L = cyclam) and one mole of nitrogen gas is evolved, the chromium metal center is oxidized from a d3 Cr III state to a d1 CrV state, however, the overall charge on the [CrV(N)(N3)(L)] + cation remains the same at +1 in the cis complexes.

Trans-diazidocyclamchromium(III)X complexes have been studied for many years as a method of synthesizing nitridochromium(V) complexes and much useful information has been realized because of this research. However, when irradiated in solution six coordinate trans-diazido complexes result in dinuclear trans-nitrido complexes through a bridging azide ligand, and there haven't been any studies on the photolysis reaction in the solid state. There hasn't been a study on the lattice and structural factors influencing the reaction in the solid state, nor is it possible to discern the reactive azide ligand in the trans species due to symmetry considerations.

Although a cis-diazidochromium(III) complex has been studied, the solid state photolysis product was never characterized and the photolysis product from solution was also determined to be a dinuclear species. Therefore, cis-diazidocyclamchromium(III) complexes and their photolysis products have not been studied in depth in the solid state nor in solution, for that matter. The research presented here demonstrates that cis-diazidocyclamchromium(III) complexes give uninuclear nitrido complexes upon photolysis in the solid state. This fact can give much useful information about the crystal dynamics that influence the reaction, including which azide ligand reacts with light to form the nitrido species and the reasons why. In this research, where possible, both the diazido and nitrido complexes have been characterized by single crystal X-ray diffraction. The ultimate goal of this research is to discover why nitrogen gas is evolved from a preferential azide ligand and to use single crystal x-ray diffraction to follow the light activated reaction of the diazido complex as it evolves nitrogen gas and forms the nitrido product to understand what factors influence these solid state reactions.

Both the cis and trans-diazidochromium(III) complexes have been synthesized and characterized during this research. Many complexes that hadn't been synthesized and characterized yet were synthesized and characterized by single crystal X-ray crystallography during this research endeavor. All of the nitridochromium(V) complexes proved to be uninuclear when reacted in the solid state and then characterized by single crystal X-ray crystallography. Only three of the cis-diazidochromium(III) complexes are covered in this thesis, but they are indicative of the varied structures and solid state reactions that are found in this particular chromium complex.

Indexing (document details)
Advisor: Olmstead, Marilyn M.
Commitee: Balch, Alan, Osterloh, Frank
School: University of California, Davis
Department: Chemistry
School Location: United States -- California
Source: MAI 48/01M, Masters Abstracts International
Subjects: Analytical chemistry, Inorganic chemistry
Keywords: Cis-diazidocyclamchromium(iii), Cis-nitridoazidocyclamchromium(v), Polymorph, Topochemical reaction, Topotactical reaction
Publication Number: 1468983
ISBN: 978-1-109-33404-3
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