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

A series of nitrido- and trans-dioxorhenium(V) complexes with substituted d ppe 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)( 2)Cl](+) and [Re(O)(2)(dmppe)(2)](+) have been determined by X-ray crystall ography. The electronic absorption bands of the nitrido complexes at ca. 23 0-300 nm are assigned as intraligand and ligand-to-metal charge-transfer tr ansitions [p(pi)(N3-)-->d(pi)*(Re) and p(pi)(Cl-)-->d(pi)*(Re)] and the wea k absorption at ca. 360-480 nm as a (d(xy))(2) --> (d(xy))(1)(d(pi)*)(1) tr ansition (d(pi)* = d(xz), d(yz)). All these complexes display long-lived so lid-state photoluminescence which is likely to be derived from the [(d(xy)) (1)(d(pi)*)(1)] triplet state. They also show emission in fluid solution. B imolecular quenching has been studied for [Re(N)(dmppe)(2)(MeCN)](2+). (C) 2000 Elsevier Science S.A. All rights reserved.