Investigation of Mixed Oxidation State Cyanide-Bridged Re^VOxo (acac₂en/pn) and Re^I(bipy)(CO)₃ Complexes

A series of cyanide-bridged complexes that combine a low-valent photoacceptor rhenium(I) metal center with an electroactive midvalent rhenium(V) complex were prepared. The synthesis involved the preparation of novel asymmetric rhenium(V) oxo compounds, cis-ReVO(CN)(acac2en) (1) and cis-ReVO(CN)(acac2pn) (2), formed by reacting trans-[ReVO(OH2)(acac2en)]Cl or trans-ReVO(acac2pn)Cl with [NBu4][CN]. The μ-bridged cyanide mixed-oxidation ReV–ReI complexes were prepared by incubating the asymmetric complexes, 1 or 2, with fac-[ReI(bipy)(CO)3][OTf] to yield cis-[ReVO(acac2en)(μ-CN-1κC:2κN)-fac-ReI(bipy)(CO)3][PF6] (3) and [cis-ReVO(acac2pn)(μ-CN-1κC:2κN)-fac-ReI(bipy)(CO)3][PF6] (4), respectively.