Complex reduction chemistry of (abpy)PtCl2, abpy = 2,2'-azobispyridine: formation of cyclic [(micro,eta2:eta1-abpy)PtCl]2(2+) with a new coordination mode for abpy and a near-infrared ligand-to-ligand intervalence charge transfer absorption of the one-electron reduced state.
The structurally characterized (abpy)PtCl2, abpy = 2,2'-azobispyridine, reveals a strong metal/ligand pi interaction as supported by DFT calculations. Unexpectedly, its chemical or electrochemical reduction occurs irreversibly to yield EPR-detectable [(micro,eta2:eta2-abpy)[PtCl2]2]*- and, as the main product of chloride dissociation, the structurally identified and DFT-calculated dinuclear [(micro,eta2:eta1-abpy)PtCl]2(2+) with a novel coordination mode for abpy and isolated as tetrachlorozincate. Stepwise reversible one-electron reduction of that dimer, separated by 0.24 V, exhibits an intense near-infrared band for the monocationic intermediate [(abpy(-I))(abpy)Pt2Cl2]*+ at 1220 nm (epsilon = 3370 M(-1) cm(-1)) which is attributed to a ligand-to-ligand intervalence charge-transfer transition.
Dogan
Akbey
A
Institut für Anorganische Chemie, Universität Stuttgart, Pfaffenwaldring 55, D-70550 Stuttgart, Germany.
Sarkar
Biprajit
B
Klein
Axel
A
Lissner
Falk
F
Schleid
Thomas
T
Fiedler
Jan
J
Zális
Stanislav
S
Jain
Vimal K
VK
Kaim
Wolfgang
W