Transition metal allyls and hydrides as chemical vapor deposition precursors

Gozum, John Ekrem

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https://hdl.handle.net/2142/21979 Copy

Description

Title

Transition metal allyls and hydrides as chemical vapor deposition precursors

Author(s)

Gozum, John Ekrem

Issue Date

1991

Department of Study

Chemistry

Discipline

Chemistry

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

• Chemistry, Inorganic
• Physics, Electricity and Magnetism
• Engineering, Materials Science

Language

eng

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.

Type of Resource

text

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Copyright and License Information

Copyright 1991 Gozum, John Ekrem

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