Investigations into ligand substitutions of rhenium and molybdenum d4 hexanuclear clusters and the synthesis and characterization of aurated pyrene and thiophene derivatives.

摘要

Ligand substitution reactions were performed on d4 rhenium and molybdenum hexanuclear clusters. For the [Re6(mu3-Q) 8]2+ clusters, where Q= S, Se, varying amounts of tributylphosphine and reaction times yielded multiply substituted clusters. Phosphine substituted reactions were monitored by 31P and 1H NMR as well as mass spectrometry. 31P NMR showed substitution through downfield shifts, for the [Re6S8]2+ clusters, and upfield for that of the [Re6Se8]2+ clusters from the free tributylphosphine ligand, while mass spectrometry determined the amount of bound phosphines (four or five). Cis-, trans-, and penta-phosphine clusters were generated from these reactions. Triflates replaced apical chlorides on the Mo(II) cluster for increasing lability. A crystal structure was determined from this cluster displaying that of a [Mo6Cl8]4+ core surrounded by six triflate ligands bound through oxygen. Two tetraphenylphosphonium cations are also found with the structure.;Base-promoted transmetalation was used to attach phosphine gold(I) fragments to the ends of pyrene. Three new compounds were generated with tricyclohexylphosphine- and triphenylphosphinegold(I) at the 2- and 2,7-positions. 31P and 1H NMR confirm reactions went to completion with no traces of the starting phosphine. Diffraction quality crystals were reported for two of the products. Binding of the phosphine causes a red xi shifting and increase of the absorbance which is further enhanced with additional gold(I) ligands.;Finally, diaurated bithiophene was produced from a boron transmetalation reaction. Triphenylphosphinegold bromide provided a suitable starting ligand for the replacement of terminal boropinacolates on the bithiophene. Reaction monitoring through multinuclear spectroscopy and mass spectrometry determined a diaurated species. A crystal structure allowed visual confirmation of the complex demonstrating the triphenylphosphinegold(I) ligand bound to the carbon adjacent to the sulfur atom. In agreement with aurated pyrenes, phosphine binding both red shifts and increases the absorbance. Further evaluation would enable studies of its optoelectronics properties.