1. 2,3-Di(2-pyridyl)-5-phenylpyrazine: A NN-CNN-Type Bridging Ligand for Dinuclear Transition-Metal Complexes.
- Author
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Wu, Si ‐ Hai, Zhong, Yu ‐ Wu, and Yao, Jiannian
- Subjects
BRIDGING ligands ,TRANSITION metal compounds ,BIMETALLIC catalysts ,RUTHENIUM ,HYDROGEN atom ,PYRIDYL compounds - Abstract
A new bridging ligand, 2,3-di(2-pyridyl)-5-phenylpyrazine (dpppzH), has been synthesized. This ligand was designed so that it could bind two metals through a NN-CNN-type coordination mode. The reaction of dpppzH with cis-[(bpy)
2 RuCl2 ] (bpy=2,2′-bipyridine) affords monoruthenium complex [(bpy)2 Ru(dpppzH)]2+ ( 12+) in 64 % yield, in which dpppzH behaves as a NN bidentate ligand. The asymmetric biruthenium complex [(bpy)2 Ru(dpppz)Ru(Mebip)]3+ ( 23+) was prepared from complex 12+ and [(Mebip)RuCl3 ] (Mebip=bis( N-methylbenzimidazolyl)pyridine), in which one hydrogen atom on the phenyl ring of dpppzH is lost and the bridging ligand binds to the second ruthenium atom in a CNN tridentate fashion. In addition, the RuPt heterobimetallic complex [(bpy)2 Ru(dpppz)Pt(CCPh)]2+ ( 42+) has been prepared from complex 12+, in which the bridging ligand binds to the platinum atom through a CNN binding mode. The electronic properties of these complexes have been probed by using electrochemical and spectroscopic techniques and studied by theoretical calculations. Complex 12+ is emissive at room temperature, with an emission λmax =695 nm. No emission was detected for complex 23+ at room temperature in MeCN, whereas complex 42+ displayed an emission at about 750 nm. The emission properties of these complexes are compared to those of previously reported Ru and RuPt bimetallic complexes with a related ligand, 2,3-di(2-pyridyl)-5,6-diphenylpyrazine. [ABSTRACT FROM AUTHOR]- Published
- 2013
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