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-BrC
6H
2(CH
2NMe
2)
2-3,5}-2,2':6',2' '-terpyridine. Mononuclear species[PdX(
TP)] (X = Br, Cl), [Ru(
TPBr)(tpy)](PF
6)
2, and [Ru(
TPBr)
2](PF
6)
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)](PF
6)
2 (
7) and [Ru(
TPPdCl)
2](PF
6)
2 (
8). The molecular structures in the solid state of [PdBr(
TP)] (
4a) and [Ru(
TPBr)
2](PF
6)
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
![](/images/entities/rarr.gif)
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)](PF
6)
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.