Date of Award
Chemistry and Biochemistry
Stephan, D. W.,
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A variety of complexes bearing the phosphinimide ligand, ranging from transition metal to main-group compounds, have been investigated. Reduction of CpTi(NPt-Bu3)Cl2 by magnesium powder resulted in the formation of the dimeric Ti(III)-species (CpTi(NPt-Bu3)(mu-Cl))2 2.1 , which was investigated by a single crystal EPR study. Reduction of CpTi(NPt-Bu3)Cl2 in the presence of 2,3-dimethyl-1,3-butadiene resulted in the formation of the butadiene complex CpTi(NPt-Bu3)(eta2-CH2C(CH3)C(CH 3)CH2) 2.2. The synthesis and reactivity of a variety of Cp*Ta-phosphinimide complexes have been explored. Reaction of stoichiometric amounts of R3PNTMS with Cp*TaCl4 afforded the complexes Cp*Ta(NPR3)Cl 3 (R = t-Bu3 3.1, i-Pr3 3.2). Further derivatization of 3.1 and 3.2 with a variety of alkylating reagents proved facile. The steric demand of the phosphinimide ligand in combination with the Cp*-ligand was evidenced in the reaction of Cp*Ta(NPR3)Cl 3 with 3 equivalents of BnMgCl, yielding the alkylidene Cp*Ta(NPR 3)(CHPh)(CH2Ph) 3.7. Addition of Mel to 3.7 produced the metallacycle Cp*Ta(NPR3)(eta2 -CHPhCH2)(CH2Ph) 3.9. The beta-hydride elimination products Cp*Ta(NPR3)(eta2-CH 2CH2)L, (L = Cl 3.10, Et 3.12), were isolated when 3.1 was reacted with 2 or 3 equivalents of EtMgCl, respectively. Cationic tantalum phosphinimide complexes such as [Cp*Ta(NP t-Bu3)X2] (X = Cl 3.13, Me = 3.16) were formed by reacting Cp*Ta(NPR3)X3 with [Ph3C][B(C6F5)4]. Zwitterionic complexes were synthesized by treatment of 3.1 or 3.10 with B(C6F5)3 to form Cp*Ta(NPt-Bu 3)Me2(MeB(C6F5)3) 3.17 and Cp*Ta(NPt-Bu3)(Cl)CH2CH 2B(C6F5)3 3.22. Synthetic routes to boron based phosphinimide complexes have been investigated. Reaction of 2 equivalents of [Li][NPt-Bu3] with BCl3 resulted in the spontaneous formation of a unique borinium cation [(t-Bu3PN)2B][Cl], which exists as a tight ion pair in unpolar solvents. Silylated phosphinimines such as R3PNTMS exhibit two different modes of reactivity towards B(C6F5)3 depending on the steric demand of the R-groups on phosphorus. B(C6F 5)3 reacts either as electron pair acceptor or methyl group abstractor to give Me3PN(BC6F5)3)SiMe 3 4.15 and [i-Pr3PNSi(Me 2)(NPi-Pr3)SiMe3)][MeB(C 6F5)3)] 4.16. Finally a series of mono-, di- and tri-substituted tin phosphinimide complexes of the form R3PNxSnL4-x (R = t-Bu, i-Pr, L = alkyl, aryl) were synthesized. The chemistry described herein provides unique insights into the reactivity of early transition metals as well as main group compounds, incurred by the utilization of bulky phosphinimide ligands.Dept. of Chemistry and Biochemistry. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis2002 .C675. Source: Dissertation Abstracts International, Volume: 64-01, Section: B, page: 0201. Adviser: D. W. Stephan. Thesis (Ph.D.)--University of Windsor (Canada), 2002.
Courtenay, Silke., "Synthesis and reactivity of group 4, 5, 13, and 14 phosphinimide complexes." (2002). Electronic Theses and Dissertations. 3694.