Oxoalkyls of rhenium-(V) and-(VI). X-Ray crystal structures of (Me4ReO)2Mg(thf)4,[(Me3SiCH2)4ReO]2Mg(thf)2, Re2O3Me6 and Re2O3(CH2SiMe3)6

Abstract

The interaction of Grignard reagents with Re₂O₇, [Me₃NH][ReO₄], ReOCl₄, or ReOCl₃(PPh₃)₂ leads to the diamagnetic rhenium(V) complexes (Me₄ReO)₂Mg(thf), and [(Me₃SiCH₂)₄ReO]₂Mg(thf)₂(thf = tetrahydrofuran) whose structures have been determined by X-ray crystallography and shown to consist of Mg²⁺ co-ordinated by thf and R₄ReO^–(R = Me or CH₂SiMe₃). Both rhenium(V) species can be oxidised to the previously known rhenium(VI) compounds ReOR₄ and Re₂O₃(CH₂SiMe₃)₆. A novel high-yield synthesis of Re₂O₃(CH₂SiMe₃)₆ and the preparation of the previously unknown Re₂O₃Me₆ are reported. The X-ray crystal structures of these compounds have been determined to reveal linear Re–O–Re bridges with mutually trans-ReO groups. An o-xylenediyl complex {[o-(CH₂)₂C₆H₄]₂ReO}₂Mg(thf)₄ has also been characterised.