Synthesis, structural characterisation, photophysics, photochemistry and electrochemistry of nitrido- and trans-dioxorhenium(V) complexes with substituted dppe ligands (dppe = bis(diphenylphosphino)ethane)

Abstract

A series of nitrido- and trans-dioxorhenium(V) complexes with substituted dppe ligands have been synthesised and characterised, and their photophysics and electrochemistry studied. The excited state chemistry of [Re(N)(dmppe)2(MeCN)]2+ has also been investigated. The structures of [Re(N)(dmppe)2Cl]+ and [Re(O)2(dmppe)2]+ have been determined by X-ray crystallography. The electronic absorption bands of the nitrido complexes at ca. 230-300 nm are assigned as intraligand and ligand-to-metal charge-transfer transitions [p(π)(N3-) → d(π*)(Re) and p(π)(Cl-) → d(π*)(Re)] and the weak absorption at ca. 360-480 nm as a (d(xy))2 → (d(xy))1(d(π*))1 transition (d(π*) = d(xz), d(yz)). All these complexes display long-lived solid-state photoluminescence which is likely to be derived from the [(d(xy))1(d(π*))1] triplet state. They also show emission in fluid solution. Bimolecular quenching has been studied for [Re(N)(dmppe)2(MeCN)]2+. (C) 2000 Elsevier Science S.A.