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 Title: Transition metal allyls and hydrides as chemical vapor deposition precursors Author(s): Gozum, John Ekrem Department / Program: Chemistry Discipline: Chemistry Degree Granting Institution: University of Illinois at Urbana-Champaign Degree: Ph.D. Genre: Dissertation Subject(s): Chemistry, Inorganic Physics, Electricity and Magnetism Engineering, Materials Science Abstract: Thin films of high purity palladium can be prepared at low temperature (250$\sp\circ$C) metal-organic chemical vapor deposition of bis(allyl)palladium or (cyclopentadienyl)(allyl)palladium.Metal sulfide films may be deposited from the precursors $\rm Fe\sb2S\sb2(CO)\sb6$ and Ti(S-t-Bu)$\sb4$ to give thin films of iron sulfide and titanium disulfide at low temperature.CVD of Ti(BH$\sb4)\sb3$(dme) at 200$\sp\circ$C resulted in deposition of thin films of TiB$\sb2$. The AES data establish the films as TiB$\sb{2.07}$ with less than 5% carbon and oxygen in the film interior.Passage of Zr(BH$\sb4)\sb4$ or Hf(BH$\sb4)\sb4$ through a hot zone at 250$\sp\circ$C resulted in deposition of thin films of MB$\sb2$.In order to trap some of the hydride species that may be formed from the CVD of Zr(BH$\sb4)\sb4$ and Hf(BH$\sb4)\sb4$, these precursors were thermolyzed in the presence of small alkyl phosphines. Treatment of the zirconium and hafnium tetrahydroborate complexes M(BH$\sb4)\sb4$ with trimethylphosphine yields crystals of the new polyhydride $\rm Zr\sb2H\sb3(BH\sb4)\sb5(PMe\sb3)\sb2$ and $\rm Hf\sb2H\sb3(BH\sb4)\sb5(PMe\sb3)\sb2$. Single crystal X-ray diffraction studies of the complexes reveal a distinctly asymmetric dinuclear structure bridged by three hydrogen atoms.Treatment of $\rm Zr(BH\sb4)\sb4$ or $\rm Hf(BH\sb4)\sb4$ with trimethylphosphine for extended reaction times has given two new polyhydrides of stoichiometry $\rm M\sb3H\sb6(BH\sb4)\sb6(PMe\sb3)\sb4$. The variable temperature $\sp1$H, $\sp{31}$P, and $\sp{11}$B NMR data suggest that these trinuclear compounds contain a non-cyclic M($\mu$-H)$\sb3$M($\mu$-H)$\sb3$M backbone with the phosphine and tetrahydroborate ligands distributed in 2:2:0 and 2:1:3 ratios among the three metal centers. This suggestion has been confirmed by a single crystal X-ray structure.Treatment of the M(BH$\sb4)\sb4$ complexes with the bidentate phosphine 1,2-bis(dimethyl-phosphino)ethane (dmpe) gives mononuclear hydrides of stoichiometry MH(BH$\sb4)\sb3$(dmpe)$\sb2$ or $\rm MH\sb2(BH\sb4)\sb2(dmpe)\sb2$ depending on the conditions.Treatment of the polyhydride complexes $\rm M\sb2H\sb3(BH\sb4)\sb5(PMe\sb3)\sb2$ with dmpe has given two new group 4 polyhydrides of stoichiometry $\rm M\sb2H\sb4(BH\sb4)\sb4(dmpe)\sb2$. The variable temperature NMR data suggest that these dinuclear compounds contain a M($\mu$-H)$\sb3$M backbone with the phosphine and tetrahydroborate ligands distributed in 2:0 and 1:3 ratios among the two metal centers; this has been confirmed by the single crystal X-ray structure. A terminal hydride is positioned in between the two bidentate dmpe ligands. A dynamic process exchanges these hydride environments, and a likely mechanism for this process has been proposed. Issue Date: 1991 Type: Text Language: English URI: http://hdl.handle.net/2142/21979 Rights Information: Copyright 1991 Gozum, John Ekrem Date Available in IDEALS: 2011-05-07 Identifier in Online Catalog: AAI9136603 OCLC Identifier: (UMI)AAI9136603
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