The impact of two constitutional isomers, 2-(4-BMes2-Ph)-pyridine (p-B-ppy) and 5-BMes2-2-ph-pyridine (p-ppy-B), as N,C-chelate ligands on the structures, stabilities, electronic and photophysical properties, and Lewis acidities of Pt(II) complexes has been investigated. Six Pt(II) complexes, Pt(p-B-ppy)Ph(DMSO), Pt(p-B-ppy)Ph(Py), [Pt(p-B-ppy)Ph]2(4,4’-bipy), Pt(p-ppy-B)Ph(DMSO), Pt(p-ppy-B)Ph(Py), and [Pt(p-ppy-B)Ph]2(4,4’-bipy), have been synthesized and fully characterized. The Lewis acidity of the complexes was examined by fluoride titration experiments using UV-Vis, phosphorescence, and NMR spectroscopic methods, establishing that the p-ppy-B complexes have stronger binding constants while the p-B-ppy complexes have a much lower affinity toward F-. A diboron compound with both 3-coordinate boron and 4-coordinate boron centers, (5-BMes2-2-ph-py)BMes2 (B2ppy) has been synthesized, which is luminescent but have a high sensitivity toward light. UV and ambient light cause this compound to isomerize via the formation of a C−C bond between a mesityl and the phenyl group, accompanied by a drastic color change from yellow to dark olive green. The structure of the dark color species was established by 2D NMR experiments and geometry optimization by DFT calculations. The dark color species can thermally reverse back to (5-BMes2-2-ph-py)BMes2 via the breaking of a C−C bond. The N, C-chelate ligand was found to play a key role in promoting this unusual and reversible photo–thermal isomerization process on a tetrahedral boron center. The impact of Pt(II) on the photoisomeration of four-coordinate boron center was also studied. The free ligand four-coordinate organoboron derivative B-ppy-ppy behaved in the same way as B2ppy. The photoisomeration process in the corresponding Pt(II) coupled complex (B-ppy-ppy)PtPh(t-Bu-py) is nearly completely deactivated, which may be attributed to either the low-lying 3MLCT excited state through which the excess energy in excited state was dissipated as phosphorescence or the greater π conjugation which can stabilize the excited state. / Thesis (Master, Chemistry) -- Queen's University, 2009-09-24 14:56:32.845

The objective of this thesis is to explore new reactivities and to improve luminescent properties of 7-azaindole-containing metal complexes. Selectivity for the activation of toluene and ethyl benzene has been investigated with two cationic Pt(II)(N,N-L) complexes, where N,N-L = 1,2-bis(1-N-7-azaindolyl)benzene (BAB) or bis(1-N-7-azaindolyl)methane (BAM). A high regioselectivity toward toluene and ethyl benzene benzylic C-H activation and a distinct diastereoselectivity for ethyl benzene benzylic C-H activation are demonstrated. Detailed mechanistic studies have been performed, leading to the establishment of both the intermediacy of the η3-benzylic Pt(II) complexes in the reactions and the ligand steric impacts as origins for the distinct diastereoselectivity. A PtMe2 complex of 1-N-(pyridin-2-yl)-7-azaindole (NPA) has been synthesized and found to undergo facile transformation at ambient temperature, resulting in the quantitive formation of a neutral Pt4 molecular square. The mechanism of the transformation process has been examined, establishing a distinct intramolecular C-H driven self-assembly process. The geometrical impacts of the BAB and BAM ligands on the structure and stability of their fac-Pt(IV)Me3 complexes has been investigated. The BAB ligand is more effective than the BAM ligand in stabilizing the five-coordinate Pt(IV)Me3 complexes. With the BAB ligand, a five-coordinate fac-Pt(IV)Me3 complex is obtained; with the BAM ligand, two six-coordinate fac-Pt(IV)Me3 complexes are obtained. In solution, the methyl groups in the BAB complex exchange slowly, but those in the BAM complexes exchange rapidly. Several new 7-azaindolyl derivative ligands via either modifying or altering the BAM and BAB bridging groups have been developed. The syntheses, structures and reactivities of their Pt(II) complexes have been examined, leading to the finding of an unconventional C-Sn oxidative addition reaction. The modification of the NPA ligand via the incorporation of a triarylboron group has been carried out. Several novel Pt(II) and Cu(I) complexes have been synthesized and studied. A Cu(I) complex is found to display exceptionally bright ambient temperature phosphorescence. A series of dinuclear Cu(I) compounds of the 1,2,3,4-tetra(1-N-7-azaindolyl)benzene (TTAB) ligand have been synthesized and examined. The close contacts between the TTAB bridging phenyl ring and the Cu(I) centers are present in the complexes. / Thesis (Ph.D, Chemistry) -- Queen's University, 2008-05-21 18:10:58.628