Reactions of the Dirhenium(II) Complexes Re₂X₄(μ-dppm)₂ (X = Cl, Br; dppm = Ph₂PCH₂PPh₂) with Isocyanides. 13. Identification of a New Structural Isomer of the Dirhenium Cation [Re₂Cl₃(μ-dppm)₂(CO)(CNXyl)₂]⁺ and Its Isomerization Behavior. Structural Characterization of (XylNC)ClRe(μ-Cl)(μ-CNXyl)(μ-dppm)₂ReCl(CO)

Abstract

A yellow form of the dirhenium salts of the type [Re2Cl3(μ-dppm)2(CO)(CNXyl)2]Y (Y = Cl, O3SCF3, PF6, ReO4) has been shown to have the μ-CNXyl-bridged structure [(XylNC)ClRe(μ-Cl)(μ-CNXyl)(μ-dppm)2ReCl(CO)]+ on the basis of an X-ray crystal structure determination of its neutral paramagnetic congener. The Re−Re bond length in the structure of Re2Cl3(μ-dppm)2(CO)(CNXyl)2 is 2.7155(9) Å, in accord with the presence of a formal Re−Re bond order of 1.5. This particular cation constitutes the fourth isomer of [Re2Cl3(μ-dppm)2(CO)(CNXyl)2]+ to have been structurally characterized