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

Akbey Dogan; Biprajit Sarkar; Axel Klein; Falk Lissner; Thomas Schleid; Jan Fiedler; Stanislav Zális; Vimal K Jain; Wolfgang Kaim

doi:10.1021/ic049941t

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

Inorg Chem. 2004 Sep 20;43(19):5973-80. doi: 10.1021/ic049941t.

Authors

Akbey Dogan¹, Biprajit Sarkar, Axel Klein, Falk Lissner, Thomas Schleid, Jan Fiedler, Stanislav Zális, Vimal K Jain, Wolfgang Kaim

Affiliation

¹ Institut für Anorganische Chemie, Universität Stuttgart, Pfaffenwaldring 55, D-70550 Stuttgart, Germany.

PMID: 15360246
DOI: 10.1021/ic049941t

Abstract

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.