476164-96-2Relevant academic research and scientific papers
Example of highly stereoregulated ruthenium amidine complex formation: Synthesis, crystal structures, and spectral and redox properties of the complexes (see abstract)
Mondal, Biplab,Puranik, Vedavati G.,Lahiri, Goutam Kumar
, p. 5831 - 5836 (2008/10/08)
The reaction of Ru(trpy)Cl3 (trpy = 2,2′:6′,2″-terpyridine) with the pyridine-based imine function NpC5H4-CH=Ni -NH-C6H5 (L), incorporating an NH spacer between the imine nitrogen (Ni) and the pendant phenyl ring, in ethanol medium followed by chromatographic work up on a neutral alumina column using CH3CN/CH2Cl2 (1:4) as eluent, results in complexes of the types [Ru(trpy)(L′)](ClO4)2 (1) and [Ru(trpy)(L)Cl]ClO4 (2). Although the identity of the free ligand (L) has been retained in complex 2, the preformed imine-based potentially bidentate ligand (L) has been selectively transformed into a new class of unusual imine-amidine-based tridentate ligand, NpC5H4-CH= Ni-N(C6H5)C(CH3)=NaH (L′), in 1. The single-crystal X-ray structures of the free ligand (L) and both complexes 1 and 2 have been determined. In 2, the sixth coordination site, that is, the Cl- function, is cis to the pyridine nitrogen (Np) of L which in turn places the NH spacer away from the Ru-Cl bond, whereas, in 1, the corresponding sixth position, that is, the Ru-Na (amidine) bond, is trans to the pyridine nitrogen (Np) of L′. The trans configuration of Na with respect to the Np of L′ in 1 provides the basis for the selective L → L′ transformation in 1. The complexes exhibit strong Ru(II) → π* (trpy) MLCT transitions in the visible region and intraligand transitions in the UV region. The lowest energy MLCT band at 510 nm for 2 has been substantially blue-shifted to 478 nm in the case of 1. The reversible Ru(III)-Ru(II) couples for 1 and 2 have been observed at 0.80 and 0.59 V versus SCE, respectively. The complexes are weakly luminescent at 77 K, exhibiting emissions at λmax, 598 nm [quantum yield (θ) = 0.43 x 10-2] and 574 nm (θ = 0.28 x 10-2) for 1 and 2, respectively.
