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Synthesis of Homo and Hetero Bi and Multinuclear Complexes Containing Gold and Closed-Shell Metals Using Bridging Phosphine and Pyridine Ligands and Study of Their Emission Properties

Nayeri, Sara | 2020

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 53538 (03)
  4. University: Sharif University of Technology
  5. Department: Chemistry
  6. Advisor(s): Jamali, Sirous
  7. Abstract:
  8. In this project, multi-nucleated clusters of copper (I)-gold (I) and silver (I)-gold (I) were synthesized. Initially, two tetranuclear Au2Cu2 cluster complexes [Au2Cu2(μ-(PPh2)2py)2(μ-OH)](PF6)3, and [Au2Cu2Cl2(μ-(PPh2)2 py)2](OTf)2, have been prepared by the reactions of precursor complexes [Au2(μ-(PPh2)2py)2](OTf)2, and [Cu2(μ-(PPh2)2py)2(μ-SMe2)(OTf)2], with [Cu(NCCH3)4]PF6 and AuCl(SMe2), respectively. The crystal structures of two clusters were determined by X-ray crystallography, indicating a butterfly-shaped Au2Cu2 metal core for the first and a planar-shaped Au2Cu2 metal core for second cluster. In the first cluster, the Cu atoms occupy the edge-sharing bond, while in the second cluster, alternating Au and Cu atoms occupy the tetragon vertices. The optical properties of the clusters were investigated by experimental and computational methods. Although the first cluster displayed a luminescence vapochromic behavior in the presence several volatile organic compounds, the second indicated only an distinguishable change in its emission color when it was exposed to vapor of hydrogen-bond donor solvents. The calculations showed that the first undergoes an unsymmetrical distortion in its two-coordinated gold(I) centers upon excitation to the first triplet excited state. This distortion induces a large Stokes shift and a strong rigidochromism behavior that is unprecedented for two-coordinated gold(I) complexes.In the next part, six and five coordinated Ag(I) clusters were synthesized. The six-coordinated silver(I) complex [Au2Ag(μ-(PPh2)2py)2(OTf)2](OTf), (py = pyridine, OTf = CF3SO3), and the five-coordinated silver(I) complex [Au2Ag-(acetone)(μ-(PPh2)2py)2](PF6)3, were prepared by the reaction of the precursor complexes 1(OTf)2 and 1(PF6)2, in which 1 = [Au2(μ-(PPh2)2py)2]2+, with salt of Ag(OTf) and Ag(PF6), respectively. Also, the five-coordinated silver(I) complex [Au2Ag(μ-(PPh2)2py)2(py)(OTf)](OTf)2, was obtained by the reaction of [Au2Ag(μ-(PPh2)2py)2(OTf)2](OTf) with pyridine. These clusters were characterized using multinuclear NMR spectroscopy and elemental microanalysis. The singlecrystal X-ray diffraction analysis revealed the octahedral and distorted square pyramidal geometries around the silver(I) centers in the crystal structures of [Au2Ag(μ-(PPh2)2py)2(OTf)2](OTf) and, [Au2Ag-(acetone)(μ-(PPh2)2py)2](PF6)3 respectively; a dynamic structure was observed for cluster [Au2Ag-(acetone)(μ-(PPh2)2py)2](PF6)3 due to pendulum motion of the Ag(pyridine) moiety, which was anchored in the metallomacrocyclic unit [Au2(μ-(PPh2)2py)2]2+. Although the crystal structure of Ag(acetone) did not display disorders for the silver atom and the acetone ligand similar to that observed for Ag(Py) cluster, the low-temperature NMR spectroscopies and calculations show a dynamic structure for this cluster due to linear motion of the Ag(acetone) moiety. The reaction of the precursor complex 1(PO2F2)2 with 2 equiv of Ag(PO2F2) yielded the tetranuclear Au2Ag2 cluster [Au2Ag2(PO2F2)2(μ-(PPh2)2py)2](PO2F2)2, with a planar-shaped {Au2Ag2} metal core in which alternating Au and Ag atoms occupy the tetragon vertices and showed a strong argentophillic interaction between the silver(I) centers. All these clusters are emissive in the solid state, and the origins of their emissive excited states were determined using time-dependent DFT calculations.The last cluster showed a dual phosphorescence emission, which displays strong dependence of the contributions of each emissive component onto the excitation wavelength
  9. Keywords:
  10. Copper (I) Complexe ; Phosphine Ligand ; Pyridine Ligands ; Vapochromic ; Rigidochromic ; Binucleating Complex ; Heteronuclear Complexes ; Metal-Ligand Interaction

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