American Chemical Society
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Complex Series [Ru(tpy)(dpk)(X)]n+ (tpy = 2,2‘:6‘,2‘ ‘-Terpyridine; dpk = 2,2‘-Dipyridyl Ketone; X = Cl-, CH3CN, NO2-, NO+, NO, NO-):  Substitution and Electron Transfer, Structure, and Spectroscopy

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journal contribution
posted on 2005-08-22, 00:00 authored by Sounak Sarkar, Biprajit Sarkar, Nripen Chanda, Sanjib Kar, Shaikh M. Mobin, Jan Fiedler, Wolfgang Kaim, Goutam Kumar Lahiri
The complex framework [Ru(tpy)(dpk)]2+ has been used to study the generation and reactivity of the nitrosyl complex [Ru(tpy)(dpk)(NO)]3+ ([4]3+). Stepwise conversion of the chloro complex [Ru(tpy)(dpk)(Cl)]+ ([1]+) via [Ru(tpy)(dpk)(CH3CN)]2+ ([2]2+) and the nitro compound [Ru(tpy)(dpk)(NO2)]+ ([3]+) yielded [4]3+; all four complexes were structurally characterized as perchlorates. Electrochemical oxidation and reduction was investigated as a function of the monodentate ligand as was the IR and UV−vis spectroscopic response (absorption/emission). The kinetics of the conversion [4]3+/[3]+ in aqueous environment were also studied. Two-step reduction of [4]3+ was monitored via EPR, UV−vis, and IR (ν(NO), ν(CO)) spectroelectrochemistry to confirm the {RuNO}7 configuration of [4]2+ and to exhibit a relatively intense band at 505 nm for [4]+, attributed to a ligand-to-ligand transition originating from bound NO-.