A Novel Heteroditopic Terpyridine-Pincer Ligand as Building Block for Mono- and Heterometallic Pd(II) and Ru(II) Complexes
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- 作者：Marcella Gagliardo ; Gema Rodrí ; guez ; Henk H. Dam ; Martin Lutz ; Anthony L. Spek ; Remco W. A. Havenith ; Paolo Coppo ; Luisa De Cola ; Franti
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- 刊名：Inorganic Chemistry
- 出版年：2006
- 出版时间：March 6, 2006
- 年：2006
- 卷：45
- 期：5
- 页码：2143 - 2155
- 全文大小：361K
- 年卷期：v.45,no.5(March 6, 2006)
- ISSN：1520-510X
文摘
A palladium-catalyzed Stille coupling reaction was employed as a versatile method for the synthesis of a novelterpyridine-pincer (3, TPBr) bridging ligand, 4'-{4-BrC6H2(CH2NMe2)2-3,5}-2,2':6',2' '-terpyridine. Mononuclear species[PdX(TP)] (X = Br, Cl), [Ru(TPBr)(tpy)](PF6)2, and [Ru(TPBr)2](PF6)2, synthesized by selective metalation of theNCNBr-pincer moiety or complexation of the terpyridine of the bifunctional ligand TPBr, were used as buildingblocks for the preparation of heterodi- and trimetallic complexes [Ru(TPPdCl)(tpy)](PF6)2 (7) and [Ru(TPPdCl)2](PF6)2 (8). The molecular structures in the solid state of [PdBr(TP)] (4a) and [Ru(TPBr)2](PF6)2 (6) have beendetermined by single-crystal X-ray analysis. Electrochemical behavior and photophysical properties of the mono-and heterometallic complexes are described. All the above di- and trimetallic Ru complexes exhibit absorptionbands attributable to 1MLCT (Ru 
tpy) transitions. For the heteroleptic complexes, the transitions involving theunsubstituted tpy ligand are at a lower energy than the tpy moiety of the TPBr ligand. The absorption bandsobserved in the electronic spectra for TPBr and [PdCl(TP)] have been assigned with the aid of TD-DFT calculations.All complexes display weak emission both at room temperature and in a butyronitrile glass at 77 K. The considerablered shift of the emission maxima relative to the signal of the reference compound [Ru(tpy)2]2+ indicates stabilizationof the luminescent 3MLCT state. For the mono- and heterometallic complexes, electrochemical and spectroscopicstudies (electronic absorption and emission spectra and luminescence lifetimes recorded at room temperature and77 K in nitrile solvents), together with the information gained from IR spectroelectrochemical studies of the dimetalliccomplex [Ru(TPPdSCN)(tpy)](PF6)2, are indicative of charge redistribution through the bridging ligand TPBr. Theresults are in line with a weak coupling between the {Ru(tpy)2} chromophoric unit and the (non)metalated NCN-pincer moiety.
tpy) transitions. For the heteroleptic complexes, the transitions involving theunsubstituted tpy ligand are at a lower energy than the tpy moiety of the TPBr ligand. The absorption bandsobserved in the electronic spectra for TPBr and [PdCl(TP)] have been assigned with the aid of TD-DFT calculations.All complexes display weak emission both at room temperature and in a butyronitrile glass at 77 K. The considerablered shift of the emission maxima relative to the signal of the reference compound [Ru(tpy)2]2+ indicates stabilizationof the luminescent 3MLCT state. For the mono- and heterometallic complexes, electrochemical and spectroscopicstudies (electronic absorption and emission spectra and luminescence lifetimes recorded at room temperature and77 K in nitrile solvents), together with the information gained from IR spectroelectrochemical studies of the dimetalliccomplex [Ru(TPPdSCN)(tpy)](PF6)2, are indicative of charge redistribution through the bridging ligand TPBr. Theresults are in line with a weak coupling between the {Ru(tpy)2} chromophoric unit and the (non)metalated NCN-pincer moiety.