Spectroscopy, electrochemistry and catalytic properties of rutheniumII complexes containing the tetradentate Schiff base ligand N,N′-bis(7-methyl-2-pyridylmethylene)-1,3-diiminopropane
摘要:
The complexes trans-[RuCl2(bpydip)] and trans-[Ru(OH2)(2)(bpydip)](PF6)(2), where bpydip is the tetradentate Schiff base ligand, N,N'-bis(7-methyl-2-pyridylmethylene)-1,3-diiminopropane, have been synthesized and characterized by elemental analysis, cyclic voltammetry, UV-Vis, FTIR and H-1 NMR spectroscopy. The electronic spectrum of the trans -[RuCl2(bpydip)] complex has been successfully simulated on the basis of the ZINDO/S method, supporting the assignment of the absorption bands at 644, 607, 458, 418 and 374 nm to Ru-11(d(pi)) --> bpydip(p(pi)*) charge-transfer transitions, and at 282 nm, to a bpydip (pi --> pi*) intraligand transition. The electrochemistry of this complex is characterized by a reversible pair of waves at +0.30 and -1.70 V, ascribed to the Ru-111/11 and bpydip(0/-1) redox couples, respectively. In contact with water, the trans-[RuCl2(bpydip)] complex spontaneously and quantitatively converts into the aqua complex, leading to pronounced changes in the electronic and electrochemical behavior. A remarkable activity in the epoxidation of cyclohexene in the presence of iodosobenzene (PhIO) has been observed for the aqua complex. (C) 2002 Elsevier Science B.V. All rights reserved.
De Souza, Vagner Roberto; Da Costa Ferreira, Ana Maria; Toma, Henrique Eisi, Journal of the Chemical Society, Dalton Transactions, 2003, # 3, p. 458 - 463