Rhenium. Part XIX. A new isothiocyanato complex of quadrivalent rhenium

Summary Reaction between K₂[ReI₆] and KSCN in boiling MeOH or in the melt gave [Re(NCS)₆]^2– and a weakly paramagnetic species, isolated as its Cs salt. Tl, Me₄N and other salts of this species have been isolated from the reaction medium of from the Cs salt by metathesis. On the basis of magnetic susceptibility and i.r. spectra the new complex has been formulated as [Re₂(NCS)₁₂]^4– containing metalmetal bond and no bridging thiocyanate. The Me₄N salt has also been isolated by bioling aqueous solutions of HReO₄ and HSCN and then adding Me₄NCL. A pyridinium salt, formulated as (pyH)₄[Re₂(NCS)₁₂], has been obtained by boiling [ReO₂py₄]NCS with aqueous HSCN. The two complex species [Re(NCS)₆]^2– and [Re₂(NCS)₁₂]^4– show distinctly different magnetic moment and electronic spectra.