A trimetallic supramolecular complex of osmium(II) and rhodium(III) displaying MLCT transitions in the near-IR

The light absorbing synthon [(tpy)OsCl(dpp)](PF6) has been prepared and reacted with RhCl3 · 3H2O to form the title complex [(tpy)OsCl(dpp)2RhCl2](PF6)3, tpy = 2,2′:6′,2″-terpyridine, dpp = 2,3-bis(2-pyridyl)pyrazine. Redox studies of [(tpy)OsCl(dpp)2RhCl2](PF6)3 indicate a lowest lying acceptor orbital that is Rh(dσ∗) based. Electronic absorption spectra of the trimetallic supramolecule and monometallic synthon show that each absorbs in the UV, visible and near-IR, with the title complex absorbing strongly throughout the range of 200-1000 nm.