Title

Sterically bulky nitrogen based ligands: New chelate complexes and applications in dehydrocoupling catalysis.

Date of Award

2005

Degree Type

Dissertation

Degree Name

Ph.D.

Department

Chemistry and Biochemistry

Keywords

Chemistry, Inorganic.

Rights

CC BY-NC-ND 4.0

Abstract

Routes to the sterically bulky chelating N,N'-based ligand systems (C 6H3i-Pr2)NC(Me)CH2PPh 2(NC6H3i-Pr2) and i-Pr2C6H3N(C(Me)NC 6H3i-Pr2)2 have been developed and their chemistries with Group 13 metals, specifically aluminum and gallium have been investigated. Highlights from this work include the isolation of neutral ligand-AIR2 species (R = Me, H) which in turn form cationic species when reacted with B(C6F5) 3 or [Ph3C][B(C6F5)4]. In addition, the N-imidoyl amidine ligand i-Pr2C 6H3N(C(Me)NC6H3i-Pr 2)2 reacts with three equivalents of AlMe3 to give the species [(i-Pr2C6H 3N(C(Me)NC6H3i-Pr2) 2)AlMe2][Al2Me7], which upon heating loses CH4 to give the neutral species (i-Pr 2C6H3N(C(=CH2)NC6H 3i-Pr2)(C(Me)NC6H3 i-Pr2)AlMe2. Kinetic studies have provided insights to the mechanism of this reaction. A number of late transition metal halide complexes of the above mentioned ligand systems have been formed and derivatization reactions have been performed resulting, in some cases, isolation of systems not common in the literature such as the borane stabilized nickel (I) hydride species (i-Pr 2C6H3N)C(Me)(NC6H3 i-Pr2)C(Me)(NC6H3iPr 2)Ni(mu-H)2BEt2. In addition, the sterically bulky mu-diimine based terminally bound rhodium dinitrogen complex, NacNacRh(N 2)(COE) is isolated and is the first example of a rhodium dinitrogen compound supported by a nitrogen-based ligand system. Finally, a new titanium-based phosphine dehydrocoupling catalyst, CpTi(NP tBu3)(CH2)4, has been discovered and applications to the dehydrocoupling of primary and secondary phosphines has been investigated. Dehydrocoupling of PhPH2 results in a number of intermediates: PhP(H)(PhP)x(H)PPh (X = 0, 1), (PhP)x (X = 4, 6) and ultimately (PhP)5 as the thermodynamically favored product. Reaction of 1,2bisphosphinobenzene with catalytic amounts of CpTi(NP t-Bu3)(CH2)4 initially gives the dehydrocoupled dimer as an intermediate to the previously reported P 16 macrocycle. Dehydrocoupling of 4,5-dimethyl-1,2-bisphosphinobenzene also gives the dimer as an intermediate, however, upon further reaction the unique P10 containing molecule is isolated.Dept. of Chemistry and Biochemistry. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis2005 .M385. Source: Dissertation Abstracts International, Volume: 66-11, Section: B, page: 5975. Thesis (Ph.D.)--University of Windsor (Canada), 2005.