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Synthesis and study of phosphinothiophene compounds

University of British Columbia

The synthesis and characterization of a series of phosphinothiophenes and transition metal complexes thereof are reported. The influence of the metals on the electronic properties and the structures of the oligomers are investigated with NMR spectroscopy, X-ray crystallography, absorption and emission spectroscopy, and cyclic voltammetry. The phosphinothiophenes were characterized by absorption and emission spectroscopy, and the spectra were found to be dependent on the length of the oligothiophene. The emission from 65, 66, 68, and 69 is assigned to a π*—>n transition, whereas emission from 67 and 70 is assigned to thienyl-based, π *—> π transitions. Phosphine oxides, phosphine sulfides, and phosphonium salts of selected phosphinothiophenes were synthesized and characterized with absorption and emission spectroscopy. Au(I) complexes of the phosphinothiophenes were synthesized and characterized (79- 85). The solid state crystal structures of 82 and 85 were found to be dimers exhibiting goldgold interactions. Variable temperature NMR spectroscopy and emission spectroscopy indicate a monomer-dimer equilibrium in solution for these complexes. The X-ray crystal structure of 81 does not exhibit gold-gold interactions, and emission of the bi- and terthienyl gold complexes is assigned to π *—> π transitions of the oligothiophene. The synthesis of coordination polymers of Au(I) and Ag(I) was attempted by the reaction of 68, 69, or 70 and metal starting material. The resulting complexes exhibit lability in solution. Emission from the Au(I) complex of 68 was assigned to a metal based transition. The absorption and emission of the bi- and terthienyl Au(I) and Ag(I) complexes are similar to those of the corresponding Au(I) complexes described above. The structure of the Ag(I) complexes are dependent on the length of the oligothiophene. Pd(II) and Pt(II) complexes 99-108 exist as cis and trans isomers, depending on the metal centre and the ligand. In the solid state, 101 is the trans isomer, and exhibits intermolecular n-stacking of the terthienyl groups, whereas 105 is the cis isomer, and exhibits intramolecular 7i-stacking. The absorption spectra of the Pd and Pt complexes are very similar to the corresponding ligands, indicating weak interaction between the metal and oligothiophene. The synthesis of Ru(II) bis(bipyridine) complexes 117-119 is described. Complexes 117-119 are characterized with absorption spectroscopy and cyclic voltammetry. The absorption spectra exhibit thienyl-based π —> π* transitions and Ru—>bpy MLCT transitions. The cyclic voltammograms do not show metal-metal coupling. [Chemical Diagrams]

Text

2009-12-22

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http://hdl.handle.net/2429/17053

Chemistry

University of British Columbia

UBCV

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