Improved syntheses of tetrachloro-oxorhenium(VI) and chlorotrioxo-rhenium(VII). Synthesis of alkoxo- and dialkylamido-rhenium com-pounds. The crystal and molecular structures of di-µ-methoxo-tetramethoxo-µ-oxo-dioxodirhenium(VI)(Re–Re), bis[lithium pentaiso-propoxo-oxorhenate(VI)–lithiumchloride–tetrahydrofuran(1/1/2)], and trans-tetraphenoxobis(trimethylphosphine)rhenium(IV)

Abstract

Much improved synthetic procedures for ReOCl₄, ReO₃Cl, ReOMe₄, Li₂[ReMe₈], and ReMe₆ are described. Interaction of ReOCl₄ with methanol in the presence of amine gives the unusual alkoxo-compound (MeO)₂ ORe(µ-O)(µ-OMe)₂ ReO(OMe)₂, (A), while LiOBu^t gives ReO(OBu^t)₄, and LiOPrⁱ gives an unusual dimeric species {Li[ReO(OPrⁱ)₅]. LiCl(thf)₂}₂, (B)(thf = tetrahydrofuran. The interaction with phenol in the presence of trimethylphosphine leads to the compound trans-Re(OPh))₄(PMe₃)₂, (C), while with lithium bis (trimethylsilyl)-amide a unique four-co-ordinate rhenium(V) compound, ReO{N(SiMe₃)₂}₃, is obtained. The crystal and molecular structures of (A)–(C) have been determined by X-ray crystallography. Compound (A) is monoclinic, space group P2₁/n, a= 12.142(1), b= 15.369(1), c= 7.311(1)Å, β= 90.22(1)°, and Z= 4. Compound (B) is triclinic, space group P₁, a= 14.602(5), b= 13.363(3), c= 9.244(6)Å, α= 98.39(4), β= 102.35(5), γ= 68.71(2)°, and Z= 1. Compound (C) is monoclinic, space group P2₁/c, a= 10.079(2), b= 10.527(3),c= 14.443(3)Å, β= 97.28(2)°, and Z= 2. The structures have been refined to R values of 0.059 (A), 0.069 (B)′ and 0.055 (C) using respectively 1 965, 4 061, and 1 797 observed intensities, measured on a diffractometer.