Structural and Photophysical Study on Alkynyl Cyclometalated Pt2Pb2 and Pt2Pb Clusters

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• 作者：Álvaro Díez ; Elena Lalinde ; M. Teresa Moreno ; Santiago Ruiz
• 刊名：Organometallics
• 出版年：2016
• 出版时间：June 13, 2016
• 年：2016
• 卷：35
• 期：11
• 页码：1735-1746
• 全文大小：728K
• 年卷期：0
• ISSN：1520-6041

文摘

Neutralization reactions of (NBu₄)[Pt(bzq)(C≡CR)₂] (bzq = 7,8-benzoquinolinyl) with [Pb(HBpz₃)]Cl (pz = pyrazolyl) afford tetranuclear neutral Pt₂Pb₂ derivatives [{Pt(bzq)(C≡CR)₂}{Pb(HBpz₃)}]₂ (R = Ph, 1; C₆H₄OMe-3, 2) or the anionic trinuclear Pt₂Pb cluster (NBu₄)[{Pt(bzq)(C≡CC₆H₄CF₃-4)₂}₂{Pb(HBpz₃)}], 3, stabilized by Pt–Pb and Pb^II···η²-(C≡CR) bonding interactions in the solid state, as confirmed by X-ray crystallography. The variable-temperature ¹H NMR spectra of 3 confirm the existence of a dynamic equilibrium that averages the “Pt(bzq)(C≡CC₆H₄CF₃-4)₂” groups in solution. 1D ¹H PGSE-NMR, 2D DOSY, and ¹H variable-temperature NMR experiments for the tetranuclear clusters 1 and 2 indicate that in solution these dimers generate mainly binuclear [{Pt(bzq)(C≡CR)₂}{Pb(HBpz₃)}] units by cleavage of the Pb^II···η²-(C≡CR) interactions. All clusters exhibit phosphorescent emission in rigid media (solid, glasses) and 3 also in CH₂Cl₂ solution. The emission maxima of 1 and 2 are slightly blue-shifted in relation to the precursors, being assigned to a mixed ³MLCT/³LC (L = bzq) excited state, perturbed by the Pt–Pb bond. However, the emission maximum of 3 coincides with that of its precursor, indicating little or no involvement of the Pt–Pb bonds in the emissive state.