Titre du document / Document title

A novel heteroditopic terpyridine-pincer ligand as building block for mono- and heterometallic Pd(II) and Ru(II) complexes

Auteur(s) / Author(s)

GAGLIARDO Marcella ; RODRIGUEZ Gema ; DAM Henk H. ; LUTZ Martin ; SPEK Anthony L. ; HAVENITH Remco W. A. ; COPPO Paolo ; DE COLA Luisa ; HARTL Frantisek ; VAN KLINK Gerard P. M. ; VAN KOTEN Gerard ;

Résumé / Abstract

A palladium-catalyzed Stille coupling reaction was employed as a versatile method for the synthesis of a novel terpyridine-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 the NCNBr-pincer moiety or complexation of the terpyridine of the bifunctional ligand TPBr, were used as building blocks for the preparation of heterodi- and trimetallic complexes [Ru(TPPdCI)(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 been determined 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 absorption bands attributable to ¹MLCT (Ru - tpy) transitions. For the heteroleptic complexes, the transitions involving the unsubstituted tpy ligand are at a lower energy than the tpy moiety of the TPBr ligand. The absorption bands observed 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 considerable red shift of the emission maxima relative to the signal of the reference compound [Ru(tpy)₂]²⁺ indicates stabilization of the luminescent ³MLCT state. For the mono- and heterometallic complexes, electrochemical and spectroscopic studies (electronic absorption and emission spectra and luminescence lifetimes recorded at room temperature and 77 K in nitrile solvents), together with the information gained from IR spectroelectrochemical studies of the dimetallic complex [Ru(TPPdSCN)(tpy)](PF₆)₂, are indicative of charge redistribution through the bridging ligand TPBr. The results are in line with a weak coupling between the {Ru(tpy)₂} chromophoric unit and the (non)metalated NCN-pincer moiety.

Revue / Journal Title

Inorganic chemistry   ISSN 0020-1669   CODEN INOCAJ 

Source / Source

2006, vol. 45, n^o5, pp. 2143-2155 [13 page(s) (article)]

Langue / Language

Anglais

Editeur / Publisher

American Chemical Society, Washington, DC, ETATS-UNIS  (1962) (Revue)

Localisation / Location

INIST-CNRS, Cote INIST : 9771, 35400015667505.0370