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oai:www.ideals.illinois.edu:2142/23211 2023-07-10 col_2142_5131 col_2142_14789 com_2142_5130 com_2142_14788 com_2142_8903

Made available in DSpace on 2011-05-07T14:06:07Z (GMT). No. of bitstreams: 2 license.txt: 4922 bytes, checksum: 910b249b4beec47e7ab768910c8f966f (MD5) 9712495.pdf: 7759739 bytes, checksum: fcc679673f6ce4c38c13b54909d5edb9 (MD5) Previous issue date: 1996 Girolami, Gregory S. You, Yujian 2011-05-07T14:06:07Z 2011-05-07T14:06:07Z 10000-01-01 1996 Titanium(II) complex CpTiCl(dmpe)$\sb2$ is prepared by reducing (CpTiCl$\sb2)\sb{\rm x}$ with n-butyllithium in the presence of 1,2-bis(dimethylphosphino)ethane (dmpe). Subsequent treatment with methyllithium or n-butyllithium affords CpTiMe(dmpe)$\sb2$ and CpTiH(dmpe)$\sb2$, respectively. The crystal structures of CpTiX(dmpe)$\sb2$ (X = Cl, Me, H) show unusually long metal ligand distances. Analogous treatment of (Cp$\sp*$Ti(BH$\sb4$)Cl) $\sb2$ with n-butyllithium affords Cp$\sp*$Ti(BH$\sb4$)(PP), where PP is dmpe or (t-butyl)tris(dimethylphosphino-methyl)silane. All of these titanium(II) complexes catalyze oligomerization of ethylene to 1-butene, 2-ethyl-1-butene, and 3-methyl-1-pentene, probably via metallacyclopentane intermediates. Oxidations of the neutral titanium(II) complexes with 1,1$\sp\prime$-dimethylferrocinium salts afford the first examples of cationic alkyltitanium(III) complexes: (CpTiX(dmpe)$\sb2\rbrack$ BAr$\sb4,$ where Ar = Ph or 3,5-(CF$\sb3)\sb2$C$\sb6$H$\sb3$ (FPB). Two other complexes, (TiMe$\rm \sb2(dmpe)\sb2\rbrack$ FPB and (Cp$\sp*$Ti(BH$\sb4$)(dmpe)) FPB, have been prepared by oxidation of the corresponding titanium(II) species. Crystallographic studies of (CpTiH(dmpe)$\sb2$) FPB, (TiMe$\sb2$(dmpe)$\sb2$) FPB, and (Cp$\sp*$Ti(BH$\sb4$)(dmpe)) FPB reveal that the titanium(III) cations show a lengthening of the Ti-P bond distances owing to a decrease in metal-ligand $\pi$-back-bonding. The cationic titanium(III) alkyls neither oligomerize nor polymerize ethylene. Treatment of Rh(hfac)(CH$\sb2$=CH$\sb2)\sb2$ (hfac = hexafluoroacetylacetonate) with vinyl-trimethylsilane, 1,2-bis(trimethylsilyl)acetylene, Cu(hfac)(COT), or PMe$\sb3$ affords a series of new complexes. High purity rhodium films have been deposited at 200-300 $\sp\circ$C using Rh(hfac)(CH$\sb2$ = CH$\sb2)\sb2$ as a CVD precursor. The deposition occurs via the disproportionation reaction 3 Rh(hfac)(alkene)$\sb2$ $\longrightarrow$ 2 Rh + Rh(hfac)$\sb3$ + 6 alkene. Ultra high vacuum studies show that Rh(hfac)(CH$\sb2$ = CH$\sb2)\sb2$ adsorbs molecularly on copper surfaces up to 130 K. The hfac groups are oriented perpendicular to the surface at 220 K. Reduction of rhodium(I) occurs at approximately 300 K. Decomposition of surface-bound hfac groups occurs at higher temperatures. This process does not occur under CVD conditions owing to the higher coverages characteristic of this process, which favor bimolecular reactions that lead to the assembly of the observed Rh(hfac)$\sb3$ product. Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Howard Ding (hding2@illinois.edu) on 2011-05-07T15:02:56Z Item is restricted indefinitely. Restriction data tranferred 2014-07-01T11:29:58-05:00 Original Data Group with Access UIUC Users [automated] Release Date: none Reason: ETDs are only available to UIUC Users without author permission ETDs are only available to UIUC Users without author permission U of I Only 9780591199772 AAI9712495 (UMI)AAI9712495 http://hdl.handle.net/2142/23211 eng Copyright 1996 You, Yujian Chemistry, Inorganic Engineering, Materials Science Part I. Synthesis, characterization, and reactivity of low valent organotitanium complexes. Part II. Chemical vapor deposition of rhodium metal thin films text Chemistry Chemistry University of Illinois at Urbana-Champaign Dissertation Ph.D.