Redox-Induced Intramolecular C-C Coupling of Acyclic Bis(2-pyridylmethylene)ethylenediamine on a Ru(acac) 2 Platform.

The paper documents redox-triggered C-C coupling of acyclic N , N '-bis(2-pyridylmethylene)ethylenediamine (BPE) to yield 2,3-bis(2-pyridyl)pyrazine (DPP) upon coordination to an electron-rich {Ru(acac) 2 } (acac = acetylacetonate) unit. This led to DPP-bridged [{Ru(acac) 2 } 2 (DPP)] 0/+ ( 2 and [ 2 ]ClO 4 ) along with the unperturbed BPE-bridged [{Ru(acac) 2 } 2 (BPE)] ( 1 ). On the contrary, electron-poor {Ru(Cl)(H)(CO)(PPh 3 ) 3 } yielded BPE-bridged [ 3 ](ClO 4 ) 2 as an exclusive product. Synergistic metal (Ru)-ligand (BPE) redox participation toward chemical noninnocence of the Schiff base ligand and DPP-mediated electronic communication in Ru II Ru III -derived [ 2 ]ClO 4 are addressed.